>I have a report with a footnote that should only print when one or more detail lines passes a test. I have been playing with setting report variables in the detail's on entry and on exit run statements, and setting the print when for the field, but can't seem to get it to work.
>How should I go about this?

Set up a variable FOOTNOTE with IIF(any condition met, 1, 0), and set it to calculate its sum and to reset itself on a group end.

In the PRINT WHEN of the footnote, specify FOOTNOTE>0.

HTH!