Oracle Forms

Hi experts,
my form is very simple it is containing just one text field and one button. In the text field user have to enter one valid date and after pressing the button he will get required data in excel sheel.

But it is giving FRM-40734 Internal Error PL/SQL error occurred .

The cursor is very simple.

select * from emp where doj=:join_date;


but when i am pressing the button it is inserting first few columns of
first line but after that is not progressing. I have ommited some fields but it is not working.

when i am closing the runtime form it is giving me this message.

MICROSOFT VISUAL C++ RUNTIME LIBRARY
PROGRAM C:\D2K\BIN\IFDBG60.EXE
FILE E:\F994W32\SRC\IC\INC.C
LINE 375

EXPRESSION elt!=(icne*)0

can you people please tell me what should i do.

Regards
Rajat