Trunk supervision keys

[ccna4481]

I setup a 4035T set as a regular extension/user. I gave it 4 trunk supervision keys (not trunk group but trunk supervision). When an inbound call comes in on a trunk the corresponding trunk supervision key lights/rings....the user can pickup the call by pressing that button. When they push the hold button it "should" but that inbound caller on hold on the trunk supervision key. This way if someone else with trunk supervision sees that someone is onhold on that trunk they can pick it up. Whats happening is when the user puts the inbound caller on hold its goes on local hold and doesnt show as being on hold on the trunk. Any ideas as to whats not right???

Thanks in advance!