Problems inserting Job Task through Page Webservice

Hi everyone,

I have exposed Page 1002 as a web service and want to read (works like a charm) but also insert Job Tasks through an ASP.NET application.

This is the code snippet I'm using:

                try
                {
                    Job_Planning_Line_Line line = new Job_Planning_Line_Line();
                    line.Description = description;
                    line.Job_Task_No = lineNo;
                    line.Job_No = projectNo;
                    line.Planning_DateSpecified = true;
                    line.Planning_Date = DateTime.Now;
                    //line.No = "MARLIES";
                    //line.Quantity = hours;
                    
                    
                    List <Job_Planning_Line_Line> lines = new List<Job_Planning_Line_Line>();
                    lines.Add(line);

                    ProjectLines pl = new ProjectLines();
                    pl.Job_No = projectNo;
                    pl.Job_Planning_Line_Line = lines.ToArray();
                    pl.Description = description;
                    pl.Job_Task_No = lineNo;
                    pl.Job_Task_Type = Job_Task_Type.Posting;

                    service.Create(ref pl);

                    pl.Job_Planning_Line_Line[0].No = "MARLIES";                 
                    pl.Job_Planning_Line_Line[0].Quantity = hours;

                    service.Update(ref pl);
                }
                catch (Exception ex)
                {
                    System.Diagnostics.Debug.WriteLine(ex.ToString());
                    //throw ex;
                }

Inserting the Job Task alone works great. I also want to insert a Job Planning Line at the same time, but as soon as i try to set the "(Resource)No." i get this error:

System.Web.Services.Protocols.SoapException: Property "Editable" for Job Planning Line Subform is invalid!

It makes no difference if i set it before the "Create" or afterwards and then call "Update". When i check the properties of the "No." Field in the subform mentioned the value of Editable is the global "No.Editable" which is set to True in OnInit of the page. So i guess OnInit is not called when operating with page webservices?

What possibilities do i have to work around this? Setting "Editable" to True is not an option and i wan't avoid creating Codeunit Webservices as much as possible (actually i'm no Dynamics NAV developer at all ).