VB.NET - Update Command not responding for Oracle XE?

I am using this command types whiling selecting in Oracle.

But it is not responding for Update command;

Dim lTT1 As New OracleConnection(Me.Connessione)
        Dim lTCIM1 As New OracleCommand()
        lTCIM1.Connection = lTT1
        lTCIM1.CommandType = CommandType.Text
        lTCIM1.CommandText = "Update DRUG Set DRNAM = 'Alchol' Where DRNAM = 'Alkol';"
        lTT1.Open()
        lTCIM1.ExecuteNonQuery()
        lTT1.Close()

Whats wrong?

Use a Try...Catch Block to see what error is generated.

Try
  Conn.Open  
  Cmd.ExececuteNonQuery
Catch ex as exception
   messagebox.show(ex.message)
Finally
  Conn.close
End Try