What you are using for the UDF_Delivery_By$ looks correct.  However, for the SalesOrderNo$, if you are not selecting a range or actual less/greater than value, i don't think you need to bother including it.  Also, a better way to get ALL is to use A as the operand, i don't think you would have to bother setting Value1$ or Value2$ in this case.  Refer to the following link for more info on report selections.

File Layouts and Program Information - SY_Selection (sage.com)

Thanks, David.  I have already tried excluding the portion for SalesOrderNo$ selection, but it did not help.  I am still getting all unprinted SOs and the date parameter is being ignored.  Any other suggestions?  And thank you very much for your feedback.

What are the returned values looking like when you are setting the filter up for the UDF_Delivery_By$?

Since you are doing "Less than" on "12/3/2021", can you try using a tighter filter or range instead? Maybe try using "Equal to" on a known good value?

Unfortunately, I've done that, also.  No go.  Totally ignores my filter.  Would it help if I pasted the entire script?

Also, if all else fails and you are not previewing the report, it may be possible to use the report object's SetReportWhereClause method.  You pass it a string that is similar to the filter used with GetResultSets.  It always seems to return a 0 even when it succeeds by the way.

I know for sure that SetReportWhereClause can be used with the ProcessReportWorkTable method but I'm not positive it will work with the ProcessReport method so this may or may not work for you.

Here are some samples from when I was testing an inventory report.  Replace the "Character" with "Chr".  The forum doesn't like "Chr" within code samples.

sWhereClause = ""
' Product Line equal to "FD&A".
	sWhereClause = "CI_Item=UCS(~ProductLine$)=UCS(""FD&A"");"
	
' Item Code Begins with "2" And Product Line Equal to "FD&A".
	sWhereClause = "CI_Item=MID(UCS(~ItemCode$),1,1)=UCS(""2"") AND UCS(~ProductLine$)=UCS(""FD&A"");"
	
' Item Code Equal to "2551-3-50" And Product Line Equal to "FD&A".
	sWhereClause = "CI_Item=UCS(~ItemCode$)=UCS(""2551-3-50"") AND UCS(~ProductLine$)=UCS(""FD&A"");"
	
' Item Code Greater than or equal to "2".
	sWhereClause = "CI_Item=UCS(~ItemCode$)>=UCS(""2"");"
	
' Item Code in a range from "D" to "E". The Character(0) and Character(255) are added to the begin and end respectfully to make sure the range is proper if you were to specify "D" and "D" as the Begin and End, which is essentially a "Begins with" anyway.
	sRangeBegin = "D"
	sRangeEnd = "G"
	sRangeBegin = sRangeBegin & Character(0)
	sRangeEnd = sRangeEnd & Character(255)
	sWhereClause = "CI_Item=UCS(~ItemCode$)>=UCS(""" & sRangeBegin & """) AND UCS(~ItemCode$)<=UCS(""" & sRangeEnd & """);"

Possibly at least the portions of the script that contain the oSO object. 

Have you tried using just a filter on the sales order number being equal to a specific value to see if that is even working as expected?

Yes, actually.  The specific range of SOs works.  Which is why I thought I must be coding the filter for UDF_Delivery_Date wrong.  I'll paste the oSO object related code below.  And I'm reviewing your comments regarding the SetReportWhereClause, too.  Thanks, David!  

Have you double checked the spelling of the UDF's name?

What does the data in the UDF look like in DFDM?

Be sure to convert your dates to the Sage date format.

   retval = oSS.nSetCompany(sCompany) 'removed some error checking here for legibility
	
   retval = oSS.nSetDate(sModule, sRunDate) 'removed some error checking here for legibility
   
   retval = oSS.nSetModule(sModule) 'removed some error checking here for legibility
   
	retVal = oSS.nSetProgram(oSS.nLookupTask("SO_SalesOrderPrinting_Ui")) 'removed some error checking here for legibility
	Set oSO = oScript.NewObject("SO_SalesOrderPrinting_rpt", oSS) 'removed some error checking here for legibility

        oSS.nTerminateUI() 'Terminate UI to avoid screen prompts

	If oSO.nScriptObject <> 0 Then
	oSO.oScriptObject.nDeactivateProcedure "*ALL*"
	'oSO.oScriptObject.nActivateProcedure "*ALL*" 
	End If
	
'Assign print params
        scModuleCode = oSS.sModuleCode
			ErrorLog retval, "Error getting module code.", oSO.sLastErrorMsg, sRunDate, oWriteObj, strLogFile, strTempDir
        scCompanyKey = oSS.sCompanyKey
			ErrorLog retval, "Error getting company key to " & sCompanyKey, oSO.sLastErrorMsg, sRunDate, oWriteObj, strLogFile, strTempDir
        scReportID = "": retval = oSO.nGetValue("cReportID$", scReportID)
			ErrorLog retval, "Error getting report ID.", oSO.sLastErrorMsg, sRunDate, oWriteObj, strLogFile, strTempDir
        sReportSetting = "AUTOPRINT"
		retval = oSO.nSetTemplateDesc("Plain")
			ErrorLog retval, "Error setting template to plain.", oSO.sLastErrorMsg, sRunDate, oWriteObj, strLogFile, strTempDir
			
            nRowKey = 1
            retval = oSO.nSelectReportSetting(sReportSetting)
				ErrorLog retval, "Error setting report setting.", oSO.sLastErrorMsg, sRunDate, oWriteObj, strLogFile, strTempDir
            retval = oSO.nSetKeyValue("ModuleCode$", scModuleCode)
				ErrorLog retval, "Error setting module code.", oSO.sLastErrorMsg, sRunDate, oWriteObj, strLogFile, strTempDir
            retval = oSO.nSetKeyValue("CompanyKey$", scCompanyKey)
				ErrorLog retval, "Error setting company key.", oSO.sLastErrorMsg, sRunDate, oWriteObj, strLogFile, strTempDir
            retval = oSO.nSetKeyValue("ReportID$", scReportID)
				ErrorLog retval, "Error setting report ID.", oSO.sLastErrorMsg, sRunDate, oWriteObj, strLogFile, strTempDir
            retval = oSO.nSetKeyValue("ReportSetting$", UCase(sReportSetting))
				ErrorLog retval, "Error setting report setting.", oSO.sLastErrorMsg, sRunDate, oWriteObj, strLogFile, strTempDir
            retval = oSO.nSetKeyValue("RowKey$", Right("00000" & CStr(nRowKey), 5))
				ErrorLog retval, "Error setting RowKey", oSO.sLastErrorMsg, sRunDate, oWriteObj, strLogFile, strTempDir
            retval = oSO.nSetKey()
				ErrorLog retval, "Error setting key.", oSO.sLastErrorMsg, sRunDate, oWriteObj, strLogFile, strTempDir
           ' retval = oSO.nSetValue("SelectField$", "Order Number")
				'ErrorLog retval, "Error selecting order number field.", oSO.sLastErrorMsg, sRunDate, oWriteObj, strLogFile, strTempDir
           ' retval = oSO.nSetValue("SelectFieldValue$", "Order Number")
				'ErrorLog retval, "Error selecting field value.", oSO.sLastErrorMsg, sRunDate, oWriteObj, strLogFile, strTempDir
            retval = oSO.nSetValue("KeyReference$", "<SALESORDERNO$>")
				ErrorLog retval, "Error setting key reference.", oSO.sLastErrorMsg, sRunDate, oWriteObj, strLogFile, strTempDir
			'retval = oSO.nSetValue("Tag$", "TABLE=SO_SALESORDERHEADER;COLUMN=~SalesOrderNo$")
				'ErrorLog retval, "Error setting tag.", oSO.sLastErrorMsg, sRunDate, oWriteObj, strLogFile, strTempDir
           ' retval = oSO.nSetValue("Operand$", "A") 'all orders
				'ErrorLog retval, "Error setting operand.", oSO.sLastErrorMsg, sRunDate, oWriteObj, strLogFile, strTempDir

			
			retval = oSO.nSetValue("SelectField$", "WarehouseCode")
				ErrorLog retval, "Error selecting WarehouseCode field.", oSO.sLastErrorMsg, sRunDate, oWriteObj, strLogFile, strTempDir
            retval = oSO.nSetValue("SelectFieldValue$", "WarehouseCode")
				ErrorLog retval, "Error selecting WarehouseCode field value.", oSO.sLastErrorMsg, sRunDate, oWriteObj, strLogFile, strTempDir				
			retval = oSO.nSetValue("Tag$", "TABLE=SO_SALESORDERHEADER;COLUMN=~WarehouseCode$")
				ErrorLog retval, "Error setting WarehouseCode tag.", oSO.sLastErrorMsg, sRunDate, oWriteObj, strLogFile, strTempDir
            retval = oSO.nSetValue("Operand$", "=") 
				ErrorLog retval, "Error setting WarehouseCode operand.", oSO.sLastErrorMsg, sRunDate, oWriteObj, strLogFile, strTempDir
            'retval = oSO.nSetValue("Value1$", sDelDate)
			retval = oSO.nSetValue("Value1$", "111")
				ErrorLog retval, "Error setting WarehouseCode value 1.", oSO.sLastErrorMsg, sRunDate, oWriteObj, strLogFile, strTempDir
			
			
            retval = oSO.nWrite()
				ErrorLog retval, "Error writing.", oSO.sLastErrorMsg, sRunDate, oWriteObj, strLogFile, strTempDir
            On Error Resume Next
            retval = oSO.nProcessReport("PRINT")
				ErrorLog retval, "Error printing.", oSO.sLastErrorMsg, sRunDate, oWriteObj, strLogFile, strTempDir '<<<<<<<<<<<<<<<ERROR OCCURS HERE
				if retval <> 0 then 
				ErrorLog retval, "Sales Order(s) printed successfully.", oSO.sLastErrorMsg, sRunDate, oWriteObj, strLogFile, strTempDir
				end if
            
        retval = oSS.nLogoffUser()