datagrid的问题

各位帮我看看 我是想用trans来更新datagrid修改的数据 碰到这个问题代码
private void button2_Click(object sender, System.EventArgs e)
{
this.BindingContext[this.taskDataSet].EndCurrentEdit();
UpdateTaskWithTransaction((DataSet) taskDataSet);
taskDataSet.AcceptChanges();

}public void UpdateTaskWithTransaction(DataSet taskDataSet)
{
SqlConnection _conn=new SqlConnection(CommunionSearchConfiguration.ConnectionString);
SqlTransaction trans=null;


SqlDataAdapter taskDataAdapter=new SqlDataAdapter(COMMANDTEXT,_conn);
taskDataAdapter.SelectCommand=new SqlCommand(COMMANDTEXT,_conn);

SqlCommandBuilder taskCommandBuilder=new SqlCommandBuilder(taskDataAdapter);
taskDataAdapter.InsertCommand=taskCommandBuilder.GetInsertCommand();
taskDataAdapter.DeleteCommand=taskCommandBuilder.GetDeleteCommand();
taskDataAdapter.UpdateCommand=taskCommandBuilder.GetUpdateCommand();

try
{

_conn.Open();
trans=_conn.BeginTransaction();
taskDataAdapter.InsertCommand.Transaction=trans;
taskDataAdapter.DeleteCommand.Transaction=trans;
taskDataAdapter.UpdateCommand.Transaction=trans;
//taskDataAdapter.Update(taskDataSet.Tables[TASK_TABLE].Select("","",DataViewRowState.Added));
taskDataAdapter.Update(taskDataSet.Tables[TASK_TABLE].Select("","",DataViewRowState.ModifiedCurrent));
//taskDataAdapter.Update(taskDataSet.Tables[TASK_TABLE].Select("","",DataViewRowState.Deleted));
trans.Commit();
}
catch(Exception ex) { trans.Rollback(); throw new Exception("更新数据出错",ex); } finally { if(_conn.State != ConnectionState.Closed) _conn.Close(); } }taskDataAdapter.InsertCommand=taskCommandBuilder.GetInsertCommand();这里出错"未处理的“System.Data.SqlClient.SqlException”类型的异常出现在 system.data.dll 中。其他信息: 系统错误。"
请问下　有经验的人什么原因