What form are you printing?  The "Pick Sheet Printing" has a button called Op Mgmt, that supports some of the suppressing for you, already.  If a SO Acknowledgement, try selecting only "Parent Items" (JT_158_WTparent) in Select expert, instead of suppressing lines.

Pick sheets print fine. I'm printing a sales order form. I have a work ticket and it's setup to have the parts chargeable however they don't want the parts to print on the invoice only the parent. I have a subreport in there rolling up the parts price and putting that on  parent price on the main form. It's a complex setup and I'm using a section suppression to suppress the parts and only show the parent on the main report.

You do know there is a check box in Bill of Materials called Print Components. Have you tried unchecking that box if it is checked.