What could be a reason for raise_application_error not display the message when it should (condition is met) ?
Could the client intercept those messages and suppress them ?
Any help is greatly appreciated.
Well, raise_application_error not displaying message ...... I assume it's within some DB code - DB trigger or stored proc/function.
The code may be having dbms_output.put_line but that message will be displayed only when you run this code from sql*plus or such similar tool.
If the front-end is evoking this code then the displaying message will not appear.
The UI will not know what message the DB code is trying to display.
Best strategy is to have a return string from DB code to the UI and display according.