I am trying to test each character in Pi_Entered to Pi, if wrong then highlight vbRed and move the next character. I get TTFTTTTF instead of digits. Highlight in red incorrect digits of Pi in a string. not sure what I am doing wrong.

Sub Highlight_Error_Digits()
    '
    ' After entering the digits, press the "Show Error Digits" highlighted in Red
    '
    Dim X, Pi_Str_Len As Integer
    Dim Pi_String, Pi_Entrd_String As String
    
    Pi_String = Range("$C$7")
    Pi_Entrd_String = Range("$C$6")
    Pi_Str_Len = Len(Pi_String)
    
    '
    Worksheets("Pi_Key'd_In").Activate
    For X = 1 To Pi_Str_Len
        If Mid(Pi_Entrd_String, X, 1) <> Mid(Pi_String, X, 1) Then
            Worksheets("Pi_Key'd_In").Activate
            Range("C9").Activate
            ActiveCell.Characters(Start:=Mid(Pi_Entrd_String, X, 1), Length:=1).Font.Color = vbRed
        Else
            Worksheets("Pi_Key'd_In").Activate
            Range("C9").Activate
            ActiveCell.Characters(Start:=Mid(Pi_Entrd_String, X, 1), Length:=1).Font.Color = vbBlack
        End If
    Next X
    Range("$C$9").Value = Pi_Entrd_String
End Sub