I am using Excel 2003.

I am trying to use Conditional Format for a cell that contains the following
Index, Match formula:
=IF(ISNA(INDEX('PO20-04-30-10'!S:S,MATCH('04-30-10-ByPO'!A6,'PO20-04-30-10'!B:B,0))),"",(INDEX('PO20-04-30-10'!S:S,MATCH('04-30-10-ByPO'!A6,'PO20-04-30-10'!B:B,0))))

This formula is in cell S6. I'd like it to turn yellow if the result of the
formula is less than the amount in cell H6 which is a total column in a pivot
table. When I try to do this, the result never works. I've tried greater
than another cell, less than H6, greater than 0, not equal to "", etc. I
can't get this to turn yellow under the right condition. Any ideas?