Referring to a Column Number in vba code - Found Via Function using Column Letter

[R_S_6]

Hi All.

I found the following function on-line. It outputs the Column Number for a given Column Letter.

'Function to calculate column number from column letter
Function ColumnIndex(ColumnLetter As String) As String
    Dim singlechar As String
    Dim intCode As Integer
    Dim loopCounter As Integer
        loopCounter = 0
        intCode = 0
    Do While Len(ColumnLetter) > 0
        singlechar = Right(ColumnLetter, 1)
        intCode = intCode + (26 ^ loopCounter) * (Asc(singlechar) - 64)
        loopCounter = loopCounter + 1
        ColumnLetter = Left(ColumnLetter, Len(ColumnLetter) - 1)
    Loop
        ColumnIndex = intCode
End Function

The user inputs a Column Letter into a userform textbox, 'TBCOL'. From the resulting column number from the function calculation, I wish to refer to this code in the following:

ColNum = Me.TBCOL.Text
ColNumber = ColumnIndex("" & ColNum & "")
MsgBox ColNumber

StartRange = Me.TBSTART.Text
    Sheets(SheetName).Select
    Set IDRowStart = Columns(??????).Find(what:="" & StartRange & "", After:=Range("B180"))

I have tried the following in the Columns() section:

Columns("& ColNumber &")
Columns(""& ColNumber &"")
Columns("'"& ColNumber &"'")
Columns(& ColNumber &)
Columns & ColNumber

None of the above seem to work. Hopefully the power of the 'Excel Forum' will sort this in a jiffy.

Thanks in advance
Mark