User-defined Function in VBA Excel is Not Accessible?

Question

I have this function in a module in my VBE, but when I try to access it in my userforms, I get an error because it cannot be detected by VBE:

This is the Col_Letter function:

Function Col_Letter(lngCol As Long) As String
    Dim vArr
    vArr = Split(Cells(1, lngCol).Address(True, False), "$")
    Col_Letter = vArr(0)
End Function

I also tried adding Public :

Public Function Col_Letter(lngCol As Long) As String
    Dim vArr
    vArr = Split(Cells(1, lngCol).Address(True, False), "$")
    Col_Letter = vArr(0)
End Function

Answer 1

Naming a module with the same name as a public funciton is quite a bad idea. Change the name of the Col_Letter module or the name of the function.