事务数据提交成功后，然后有显示失败！好像提交两次

 在VS2005中，写入如下语句；完成事务；在运行过程中，经常发现，写入成功后又，又显示写入失败（因为设置了主键，不能重复的）。到数据库查看数据应该成功写入；代码如下           Sql_conn.Open();
            SqlCommand Sql_Add_Cmd = Sql_conn.CreateCommand();
            Sql_Add_Cmd.CommandTimeout = 300;  //连接时限改为300秒
            SqlTransaction SqlTran = Sql_conn.BeginTransaction();
            Sql_Add_Cmd.Transaction = SqlTran;            Oracle_conn.Open();
            OracleCommand Ora_Bill_Cmd = Oracle_conn.CreateCommand();
            OracleTransaction OraTran = Oracle_conn.BeginTransaction();
            Ora_Bill_Cmd.Transaction = OraTran;
      
            using (TransactionScope transScope = new TransactionScope())
            {
                try
                {//---创建事务用-------
                    
                 FOR (i=0;i<m;i++)
                     {
                       ...
                       ...
                      插入语句
                     }                    SqlTran.Commit();                    //提交数据
                    OraTran.Commit();                    //提交数据                   
                }
                catch (Exception ex)
                {
                    SqlTran.Rollback();           //回滚数据
                    OraTran.Rollback();
                    Response.Write("----具体错误描述请看"+ex.String());
                 
                }
            }              Sql_conn.Close();
            Oracle_conn.Close();错误日志：XX写入成功！   XX写入失败，原因是主键存在！