System variables are case sensitive.

Try @DATE@

That was too simple.  I should have known that.  Thank you.

Happened to me too.

You're welcome

Where can I find a list of options with proper syntax for these output files?

The list of System Variables can be found in the Help files, Using System Variables under Working with Filters and Parameters as part of the Report Manager section.  Or, in Report Manager, select the report and then select the Filter or Parameter tab in the Properties Window. When you add a filter there is a window that opens for you to Enter Comparison Value. Pressing the @ button to the right of the drop-down field gives you the list of system variables.  I hope this helps.   system variables

Thank you!