question on master-detail form!!!!.

Hi,
  I created Master_detail form.The details are as follows:

Master has a primary key column on which it is joined to detail block. On the form,I have one field(Primary Key) in master block and several fields(columns) in the detail block and both are on the same canvas. When I run form & enter a new item in master field & corresponding details records for that master & save it,its saves fine,but when I clear form & enter same field(item) in master record & enter different detail record for the same master item,it does not save the detail record,it gives error "Oracle Unable to insert record" and when I click on history,it tells me that "ORA-00001:UNIQUE CONSTRAINT(Primary Key)VIOLATED" and cursor moves to Master Block.
  But if I query & try to insert detail record for that master,it saves.The problem comes only when I try to insert a detail record for already existing master record & also if it already had some detail records.

   Can anyone tell me,is there way to insert detail record for already existing master record other than querying and inserting detail record.

  can anyone tell me how to populate details automically if it exists for the master record when we enter the master item without manually executing the query in detail block.

Thanks in Advance.
 Ashok.
P.S:I am using forms 4.5.7.1.8 Received on Sat Jun 19 1999 - 19:41:55 CDT