Hi Siva,
Great you got your issue resolved. Now to make field disable. open exit_saplqpli_006 in which you have implemented the logic.
click on the button which is in yellow color it will direct you to se80.
open PBO module and double click in status_0100.
Here screen-name = 'ci_qals-zzname' is the field name which you created in layout.
I have implement in my system successfully.
In qa02.
in qa03.
Reward if it is help full.
Regards,
Quddus.