Null Date Issue

Had this posted to a different with no response, so I thought I would try here.

The field that I am using is unchecked for Treat blank values as "0".
I have tried: If([Project - Order Fixtures]=null,null,[Start Date]-Days([Project - Order Fixtures]))
and it gives me the Start Date, same thing when I try
If(not IsNull([Project - Order Fixtures]),[Start Date]-Days([Project - Order Fixtures]),null)

Any idea why when the Project - Order Fixtures is blank my resulting formula is not returning blank?

Thanks



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Hans Hamm
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