bad file name error #52

[isnoend07]

This function gathers all the drive letters on a USB drive. It is reporting a bad File Name at Line 90 anyone know why ?

Function BackUpBidFoldersDrive() As String
            Dim UsbDriverLetters() As String
            Dim DriveLetterToUse As String
            Dim counter As Integer
            Dim i As Integer
            Dim UsbDriveLetter As String
            Dim TmpDriveLetter As String
            Dim CdFlashDriveLetter As String
            Dim freespace As Double 'Long
            Dim MostSpace As Double
30            On Error GoTo e
      
40           counter = 0

50            For i = 65 To 90
60              If DriveType(Chr$(i)) = "removeable" Then
70                    If Chr$(i) <> "A" Then 'A shows as removal also
                          counter = counter + 1
80                        TmpDriveLetter = Chr$(i)
90                           ReDim Preserve UsbDriverLetters(counter + 1) 'error here
                             UsbDriverLetters(counter) = Chr$(i) & ":\"
                       
                   End If
               End If
            Next i