Why PSi QueueUpdateProject(jobId, sessionUid, projectDs, false) always Failed

I use PSI change the PCT_WORK_COMP of task ,Why PSi QueueUpdateProject(jobId, sessionUid, projectDs, false)  always Failed?      

                                        Guid taskUid = new Guid(dr["TaskGuid"].ToString());
                                        HTSBWebService.ProjectWebSvc.ProjectDataSet.TaskRow taskrow = projectDs.Task.FindByTASK_UIDPROJ_UID(taskUid,ProjectUid);
                                        int PercentWorkCompleted = Convert.ToInt32(dr["PercentWorkCompleted"]);
                                        taskrow.TASK_PCT_WORK_COMP = PercentWorkCompleted;

Guid jobId = Guid.NewGuid();
                            projectSvc.QueueUpdateProject(jobId, sessionUid, projectDs, false);
                            this.psiWaitForQueue(queueSystemSvc, jobId);
                            isUpdateSuccess = true;
                        }
                        catch (Exception updateEx)
                        {
                            //记录日志
                            string errorTitle = "未知错误";
                            WriteUpdateLogs(0, errorTitle, updateEx.Message, dt);
                        }

                        //Check in the project
                        bool isForceCheckIn = true;
                        Guid jobId1 = Guid.NewGuid();
                        projectSvc.QueueCheckInProject(jobId1, ProjectUid, isForceCheckIn, sessionUid, session_desc);
                        this.psiWaitForQueue(queueSystemSvc, jobId1);

                        // Publish the project.
                        Guid jobId2 = Guid.NewGuid();
                        projectSvc.QueuePublish(jobId2, ProjectUid, false, String.Empty);
                        this.psiWaitForQueue(queueSystemSvc, jobId2);
Queue request Failed for Job ID cfa7d1a6-f396-4c05-9392-d83dac9050bd.
<?xml version="1.0" encoding="utf-16"?><errinfo><dataset name="ProjectDataSet"><table name="Assignment"><row ASSN_UID="54d8d3a6-b993-4be4-87dd-90a8aafeab38" PROJ_UID="3ce7a546-b0d7-4f32-a44a-f6df8766e440"><error id="135" name="AssignmentCannotEditSummaryTask" uid="21131f77-ab7b-43d3-b42a-468d26cf8c8b" /></row></table></dataset><general><class name="Queue"><error id="26000" name="GeneralQueueJobFailed" uid="6d737c0f-b5e0-4f6b-9b45-41f2438aa30a" JobUID="cfa7d1a6-f396-4c05-9392-d83dac9050bd" ComputerName="SIBUPROJECT" GroupType="ProjectUpdate" MessageType="" MessageId="" Stage="" /></class></general></errinfo>