Oracle Forms

Hello experts,
I want to create an error message in a enter query mode.Suppose i have a field dob and the data filled
in the database in this fasion 01-jan-2008.

Suppose in the enter query mode some one enter the value 01/01/2008.It is not a suitable input for the system .For this error i want to create a error message.

I have written this code

if :system.mode = 'ENTER-QUERY' then
if error_type='FRM' and error_code=40358 then
message('please enter date as 01-jan-2008');
end if;
end if;

The trigger i have used is KEY-EXEQRY.but it is not showing any error when ever i give a input like 01/01/2008.


can you please suggest what's wrong in the coding.

Regards
Anutosh