Control Source on a form

[verdes]

I'm using access 2007

I have 2 unbound form controls that I've assigned values: one is a price field that I assign a value to the control source property using:
= DLookup.....
The dlookup works correctly.

The other field's (cost) control source is calculated:
= price * quantity

The calculation works fine.

Problem is the form is a datasheet and the user can add new records.
how do I keep from getting the #Error on the new row of these 2 fields?

 

[John Big Booty]

Have a look at the Nz().