Sqltransaction一个小问题，急


insCmd="insert into FlightDetails values('"+this.txtFlightCode.Text+"','"+this.txtAirline.Text+"','"+
this.txtDestination.Text+"','"+this.txtSourse.Text+"','"+this.txtArrival.Text+
"','"+this.txtDeparture.Text+"',"+this.cboSeats.SelectedItem.ToString()+")";


SqlTransaction objSqltran=objSqlConnection.BeginTransaction();
objSqlCommand=new SqlCommand(insCmd,objSqlConnection,objSqltran); try
{
objSqlConnection.Open();
objSqlCommand.ExecuteNonQuery();
objSqltran.Commit();
MessageBox.Show("增加成功！");
this.txtFlightCode.Enabled=false;
this.btnDelete.Enabled=true;
this.btnModify.Enabled=true;
//this.btnAdd.Enabled=false; }
catch(SqlException ex)
{
objSqltran.Rollback();
MessageBox.Show(ex.Message);
}
finally
{
objSqlConnection.Close();
}
这是我的 增加数据的代码，一运行
SqlTransaction objSqltran=objSqlConnection.BeginTransaction();就报异常？
为什么啊？怎么解决？