Method Range of Object Worksheet failed when inserting column - vba

Question

I've been working on a macro for a client. Need to insert columns based on cell values.
I use the same code for each value:
ws.range(getcolumn(currentColumn + 1) & ":" & getcolumn(currentcolumn + 3)).EntireColumn.Insert
That works fine until I hit column 50, and then I get a runtime Error of 1004 that says "Method Range of Object Worksheet Failed"
Why am I getting this error?
Here is the getColumn() function:
Function getColumn(columnNumber As Integer) As String
Dim alphaNumber As Integer
Dim iRemainder As Integer
alphaNumber = Int(columnNumber / 27)
iRemainder = columnNumber - (alphaNumber * 26)
If alphaNumber > 0 Then
getColumn = Chr(alphaNumber + 64)
End If
If iRemainder > 0 Then
getColumn = getColumn & Chr(iRemainder + 64)
End If
End Function

Answer 1

Looks like the problem is in your getColumn() function.
When currentcolumn = 50 the getColumn is returning "A[" because iRemainder is 27 so your looking for Chr(91) which is [
Taken from this post try this:
Function getColumn(columnNumber As Integer) As String
If columnNumber < 27 Then
getColumn = Chr(64 + columnNumber)
Else
getColumn = getColumn((columnNumber - 1) \ 26) & getColumn((columnNumber - 1) Mod 26 + 1)
End If
End Function
I did a basic test using this sub:
Sub insertCol()
Set ws = Sheets("Sheet1")
For currentcolumn = 1 To 60
ws.Range(getColumn(currentcolumn + 1) & ":" & getColumn(currentcolumn + 3)).EntireColumn.Insert
Next currentcolumn
End Sub