IIF is 'immediate if' (more on IIF here, i prefer to use if, then else in vb, more on if,then,else here), try this instead
Code:
Private Sub Form_Current()
If IsNull(Me!RequestforQuotesID) then
strTmp = "Null"
'note this will not make it null, but instead allocated the string 'null'
'also note no further action is required so i did not write in elseif or else
endif
Location.Requery
DoCmd.Maximize
'PrepareITtmpForSubform (strTmp)
If (IsEditable) Then
Me.AllowEdits = True
Me.Request_For_Quotes_Subform.Locked = False
Else
Me.AllowEdits = False
Me.Request_For_Quotes_Subform.Locked = True
End If
End Sub