Android Question crc computing error

Sub GetCheckSum(MyData As String) As String
    Dim CRC = 255 As Int
    If Not(MyData.StartsWith("02")) Then
        MyData = "02" & MyData
    End If
    Try
        Dim CRC = 255 As Int
        Do While MyData.Length >= 2
            CRC = Bit.Xor(CRC, Bit.ParseInt(MyData.SubString2(0, 2), 16))
            MyData = MyData.SubString(2)
        Loop
        Dim tmp(1) As Byte
        tmp(0) = CRC
        Dim tmpStr = conv.HexFromBytes(tmp) As String
        Return tmpStr
    Catch
        Log("Couldn't convert! Error was: " & LastException.Message)
        Return("00")
    End Try
 
End Sub