Customer wants to restrict editing of the field work-complete when the work-complete=100

I am using Windchill PDMLink Release 11.2 and Datecode with CPS 11.2.1.6

We have a requirement for our customer SAC. The customer wants to restrict editing of the field work-complete when the work-complete field is already 100% (work complete field of Plan Activity under project Management) We have written java code in which a adapter class extends ServiceEventListenerAdapter and the logic is written under notifyVetoableEvent. We have written xconf file which is registered under site.xconf and wt.properties file. Also restarted the server to test it. It is not working. Please suggest us if we are missing anything