How to trap when combo has no entry

[pb21]

I have a combo that the user is meant to select a value commission rate. How do I trap if the user didnt enter anything? i tried =null is null but it just squeels about wanting an object. here is the code that grabs the value:

commissionpercent = CDbl(Forms!FrmbookcourseEnhanced!CBCommission.Column(0))

I tried if(forms!.....cbcommission.column(0)=null) then...

that failed.

regards in advance.
peter

 

[EMP]

If IsNull(Forms!FrmbookcourseEnhanced!CBCommission) then

   ' do something  
 
End If

If the code is on the FrmbookcourseEnhanced form, you can use:

If IsNull(Me.CBCommission) then

   ' do something  
 
End If