Remove update for some responsibilities

11.5.10.2 applications.

I am trying to use forms personalization to prevent certain responsibilities from being able to update the vendor end Date Active field on APXVDMVD.  I have set up trigger of When_New_REcord_Instance, trigger object of Vndr and Processing of both.  The level is responsibility and I have put in the responsibility that I want to remove update from.  On the actions tab, my obj_type is Item, My target is VNDR.END_DATE_ACTIVE, my property is Update_Allowed and the value is false.  I saved this, logged out and logged back in using the responsibility that should not have update.  However, it is still possible to update this field.