Unable to update records in a table

string Conx = @"Data Source=" +

(System.IO.Path.GetDirectoryName(System.Reflection.Assembly.GetExecutingAssembly().GetName().CodeBase)) +

"\\ReaderDB.sdf;Persist Security info=False";

conn =new SqlCeConnection(Conx);

conn.Open();

SqlCeTransaction Trans = conn.BeginTransaction();

try

{

istr = "Update TblLogger set CRead=" + CRead + ",Consumption=" + Consumption + ",Status='" + cboStatus.Text + "' where WSNO='" + cellValue + "'";

comm.Connection = conn;

comm = new SqlCeCommand(istr, conn, Trans);

comm.ExecuteNonQuery();

Trans.Commit();

txtReads.Text = "";

}

catch (Exception)

{

MessageBox.Show("Data not posted").ToString();

}