Privileged Instruction when calling "Cancel" on a client dataset

Question

This is a really interesting error indeed :) I have a child form inheriting from a base form. The base form provides all sorts of virtual;abstract; services for use by children. This form uses all of them :) one of the services is a Save/Cancel system, which is coded in this way in the base form:

procedure TBaseRecordFrm.ConfirmSave(AVal: Boolean);
begin
  if AVal then
    PerformSave
  else
    PerformCancel;
  Close;
end;

The inherited form does something quite simple: in the Ok and Cancel button calls ConfirmSave with the appropriate parameter(True/False). The code for the two methods is pretty straight-forward:

procedure TActionFrm.PerformCancel;
begin
  if DMMain.CDSActionItems.State in dsEditModes then
    DMMain.CDSActionItems.Cancel;
end;

procedure TActionFrm.PerformSave;
begin
  if DMMain.CDSActionItems.State in dsEditModes then
    DMMain.CDSActionItems.Post;
end;

When pressing "Cancel", I get a "Privileged Instruction" exception. I am not doing anything spectacular as far as I can see. Anybody can shed some light, please? :)

Thank you!

Andrea