Access error with calculated field

[noclueforid]

Here is my calculation:

=DateAdd("d",-1,DateAdd("d",56,DateAdd("d",-(IIf(Weekday([Cert_Date])=1,"0",Weekday([Cert_Date]-1))),[Cert_Date])))

I get "#Error" in the field when displayed. However, when I enter the [Cert_Date] for the calculation, it does calculate. So why is the error showing?

Thanks!

[Steven Kogan]

It seems Cert_Date can't be null for the formula to work.

Try:

iif(isdate([Cert_Date]),DateAdd("d",-1,DateAdd("d",56,DateAdd("d",-(IIf(Weekday([Cert_Date])=1,"0",Weekday([Cert_Date]-1))),[Cert_Date]))),Null)

[noclueforid]

THANKS!!!!!!!!!!!!

Dave