increment number error

i have these code to auto generate member number but the highlighted line generate error 94 - invalid use of NULL:

Private Sub cmdGetNumb_Click()
'On click of button a new Member Number is generated and
'focus is moved to tFName field.
Me![nMembNum] = NewMembNum()
Me![tFName].SetFocus
'Prevent accidental click
Me![cmdGetNumb].Enabled = False
End Sub


Public Function NewMembNum() As Long

On Error GoTo NextNum_Err

Dim lngNextNum As Long

'Find highest Member number in the tblMembers table and add 1
lngNextNum = DMax("[nMembNum]", "tblMembers") + 1

'Assign function the value of the Next ID
NewMembNum = lngNextNum

'Exit function now after successful incrementing or after error message
Exit_NewMembNum:
Exit Function

'If an error occurred, display a message, then go to Exit statement
NextNum_Err:
MsgBox "Error " & Err & ": " & Error$

Resume Exit_NewMembNum

End Function

what could be wrong?

gbil,

Try:

lngNextNum = Nz(DMax("[nMembNum]", "tblMembers"), 0) + 1

DMax can return a Null, which can't be assigned to lngNextNum.

Wayne

wow. that was fast.

and the code runs without error.

thank you wayne