One checkbox working one check box not -- same code

[SeadooRider]

I have two checkboxes on my form. What I'm trying to do is if the checkbox is checked, a related field must have an entry. One checkbox is bringing up the msgbox, the other is not.

First code works:

Private Sub CkSAOntwkPOC_AfterUpdate()
If CkSAOntwkPOC = -1 And Pref_DSN = "" Then
Cancel = True
MsgBox "this record..."
Pref_DSN.setfocus
end If
End Sub

Second Code only works if the And... is left off

Private Sub CkDTSPO_AfterUpdate()
If CkDTSPO = -1 And PhoneListName = "" then
Cancel = True
MsgBox "This record requires..."
PhoneListName.setfocus
End If
End Sub

Like I said, if I take the -- And PhoneListName = "" off, it works.

What could be the difference?

Thx
Jason

[SeadooRider]

Also, the second one works if I put And PhoneListName = "1" and then if there is a 1 in the field it works correctly.
So, it has something to do with the ""

[Rabbit]

Are you sure the PhoneListName is a blank string and not a null? A null can look like a blank string but they are not the same thing. To cover both possibilites, you should use

Nz(FieldName, "") = ""

Where the Nz function converts nulls to the blank string.

[SeadooRider]

Hmm, never seen that before. I had tried Is Null but that didn't work either. the Nz thing worked great.

thx

[Rabbit]

Is Null is a SQL only thing. The equivalent in VBA code is the IsNull() function.

[SeadooRider]

Ahh, good to know, I didn't try IsNull().