how to disable/enable the fields in SIT depends upon responsibility

Customization for SITs (Special Information Types) to make it editable/read-only depending on the user responsibility is  NOT working.

There is  a Security setup in a package SEC_LIBRARY_PKG.SIT_SECURITY
Customization on Custom.pll

SIT Scenario : 'Years of Service' SIT from 'X1' responsibility should be read-only as per the setup in SEC_LIBRARY_PKG.SIT_SECURITY, but it is found Editable.

The code will be like this

getting menu name and responsibilty name into 2 varaiables.

The menu_name for X1 responsibility is 'x1 menu'

IF MENU_NAME Is ('x1 menu')

         AND SIT = 'Years of Service'

   THEN

    RETURN 0;