I have a form that has a combo box from which
users choose a family number.  After this is done, the
choice they make limits the value in a text box called
Total IFSP's (this displays the total number of IFSP's
for that particular family).  From there, a user can
enter an IFSP number into a third text box and then
view/edit that IFSP.  There is also a comand button that
gives the user the option of adding a brand new IFSP for
that family.  This all worked fine until recently, but
now when the user goes to add a new IFSP we are getting
an error message that says:  Complie error: Syntax
Error.  The code I have behind the Add IFSP command
button is:

Private Sub Command3_Click()
On Error GoTo Err_Command3_Click

   Dim stDocName As String
   Dim stLinkCriteria As String

   stDocName = "IFSP"
   DoCmd.OpenForm stDocName, , , stLinkCriteria,
acFormAdd, , Me.Family_Number
   IIf ([IFSP Number]=0,1,[IFSP Number]+1)

Exit_Command3_Click:
   Exit Sub

Err_Command3_Click:
   MsgBox Err.Description
   Resume Exit_Command3_Click
   
End Sub

I get this error whether the family has had any previous
IFSP's or not.  The user can still View/Edit any
previously entered IFSP's, just can't add any new ones.  
Any ideas as to what's going on?