Having a problem with #Num! error in date field

[Guest]

I am trying to get a field inside a form that will show 90 day difference
from another field in the same form, I've tried date serial and date add, but
will either get a blank field or an error message in the destination field.
I'm not a coder, so if there is anyway to help I'd greatly appreciate it.
Please help me with this if you can.

 

[Guest]

In the ControlSource of the field, write

= IIf([Date Field Name] Is Null, "", DateAdd("d",90,[Date Field Name]))

 

[Van T. Dinh]

Please post the expression you used as the ControlSource for the TextBox and
gives details of custom name(s) you used in the expression.

 

[Guest]

OHHH MYYYY GOODDNESSSSS!!! Thank you so much! I should have posted this
problem a long time ago! You have my deepest heart felt appreciation!

In the ControlSource of the field, write

= IIf([Date Field Name] Is Null, "", DateAdd("d",90,[Date Field Name]))

--
\\// Live Long and Prosper \\//

I am trying to get a field inside a form that will show 90 day difference
from another field in the same form, I've tried date serial and date add, but
will either get a blank field or an error message in the destination field.
I'm not a coder, so if there is anyway to help I'd greatly appreciate it.
Please help me with this if you can.