We're trying to set up a shared line and use the overlay option on our 7940's with several extensions tied to button 1. Unfortunately while this works great on one of the phones on the other 3 it seems to go through fine when hitting change in CCME but when we actually check there is no overlay, just a regular line. I thought it was a firmware issue at first but now they are all set to the same firmware version as the phone that doesn't drop the overlay and the config still won't stick on the others.

Have IOS version 12.4(13b), CCME 3.3 and

7940 firmware 7.2(2.0) - P00307020200