What error message are you getting? Would it also be possible to upload a copy of your workbook (twbx) ?
The error message I get is: "can't compare date and string values"
Try changing formula to use # instead of ' :
IF [Date1] = #01/01/2015#
From the syntax it looks like your date format is wrong. Try:
If [Date1] = #2015-01-01#
If that doesn't work, please attach a sample workbook!
Thanks Dan - that's worked!
If you have a solution to your problem please mark an answer as correct.