Function To Process String Input And Return Integer

i did some VBA quite a while back, and picking it up again.

I'm trying to get a function to read in a string, and return a value based on the string value.



Public Function value(ItemType As String) As Integer
If ItemType = " Upper" Then
value = 40
ElseIf ItemType = "Middle" Then
value = 50
ElseIf ItemType = "Lower" Then
value = 25
End If
End Function

When i tried using it at the Cell level, it keep giving error i.e. Invalid Name Error