Forms :: How To Delete Record

i m using oracle 10g forms

in one form

there are multiple records shown in this form

i m using one delete button

coding is

declare
v_yes_no varchar2(1);
begin
v_yes_no:=display_alert2('alert_2','Caution','Do you want to delete current record');

[Code]...

but when i press this button then one message shown on secreen

you can not delete this record

when i debug the form

message shown through on error trigger

i can not understand why this message ocuured

and record not deleted

no any constraint use in this form

but if i delete record from backend then records delete successfully