#Error appearing in calculated field

[ashley25]

I have created the following field to work out decimal age from a date of birth.
DECIMAL AGE: Round(((Now()-[tbl_Suspects]![DateOfBirth])/365.25),2)
It has always worked, however,access is now returning #Error for each person, I suspect because Suspects with no DoB have started to appear. Can someone help as I've tried various things from using iif is null and Nz but nothing is working.

 

[gemma-the-husky]

wouldn't nz used like this work. should return 0, for a null dob.

Round(((Now()-nz([tbl_Suspects]![DateOfBirth],now())/365.25),2)