End Google Ads 201810 - BS.net 01 --> I want to update Some Value to Marked Number Value in MarkedNumber Column

I Want to know where's the error in this code

public void UpdateMessageToIncludeMarkedNumber()
{

#region Compare to Insert Marked Number With Matching Message into Table in Database.
SqlCommand cmd = new SqlCommand();
cmd.CommandText = "update VopMessage_tbl set MarkedNumber=@MarkedNumber where Byte24=@Byte24 and Byte4=@Byte4";
cmd.Connection = con;


for (int t = 0; t < Set10bytesMessage.Count; t++)
{
MarkedNumber mNumber = (MarkedNumber)Set10bytesMessage[t];
for (int f = 0; f < Set30bytesMessage.Count; f++)
{
VopMessage vms = (VopMessage)Set30bytesMessage[f];
if (mNumber.Byte4 == vms.Byte24 & mNumber.Byte5 == vms.Byte4)
{
cmd.Parameters.AddWithValue("@Byte24", vms.Byte24);
cmd.Parameters.AddWithValue("@Byte4", vms.Byte4);
string All2BytesOfTwoMarkedNumber = mNumber.Byte4 + mNumber.Byte5;
cmd.Parameters.AddWithValue("@MarkedNumber", All2BytesOfTwoMarkedNumber);
}
else {
// cmd.Parameters.AddWithValue("@MarkedNumber", "لا يوجد");
}
}
}
con.Open();
cmd.ExecuteNonQuery();
con.Close();
#endregion
}