Error adding Administrative task using PSI GeneralObjectAlreadyEx

[Smugliy]

HI ,
I am using example from
http://msdn2.microsoft.com/en-us/library/websvctimesheet.timesheet.queuereviewtimesheet.aspx

I want to add admin task from PSI.this is a part of code from example:
TimeSheetWebSvc.TimesheetDataSet.LinesRow line =
timesheetDs.Lines.NewLinesRow();
line.TS_UID = timeSheetUid;
line.TS_LINE_UID = Guid.NewGuid();
line.TS_LINE_CLASS_UID =
tsLineClassDs.LineClasses[0].TS_LINE_CLASS_UID; // Here I receive an error
!!!!
line.TS_LINE_COMMENT = "Added by code sample.";
line.TS_LINE_STATUS =
(byte)PSLibrary.TimesheetEnum.LineStatus.NotApplicable;
line.TS_LINE_VALIDATION_TYPE =
(byte)PSLibrary.TimesheetEnum.ValidationType.Unverified;
line.TS_LINE_CACHED_ASSIGN_NAME =
tsLineClassDs.LineClasses[0].TS_LINE_CLASS_DESC;
timesheetDs.Lines.AddLinesRow(line);

If I add new Guid to line.TS_LINE_CLASS_UID I receive error "Object does not
exist"

If I add Guid to line.TS_LINE_CLASS_UID (which is already exist like in the
example) I receive error "Object already exist"

So what should I do ,maybe somebody know ,what the correct value for
TS_LINE_CLASS_UID ?????

Thanks a lot