The best tool to test if Call Admission Control (CAC) is actually being used once you have activated it is to use the Logging tool provided with Lync. The Protocol you are interested in is PDP. Another cool tool is the bandwidth monitoring tool provided in the Resource Toolkit. That will show you currently used BW and also existing limits imposed via bandwidth policies.
Should you be in a lab environment, there is a good chance you will not find any CAC entries in the PDP logfile (look for the keywords: requested,current,returned) and the monitoring tool shows Zeros throughout.
CAC is initiated from the client. Effectively the client must know to start asking for a bandwidth for it to turn up in the logs and CAC to do its magic. If the client does not know that CAC is enabled it will not ask. Thus make sure you exit out of the test clients completely and also run gpupdate /force on each test machine after you enabled CAC.
Another universal fix it when Lync clients are misbehaving is to delete the Cache file. For best results go to:
%userprofile%\AppData\Local\Microsoft\Communicator and delete every folder starting with sip_. That will clear out any cached values on your client (and the contact list too) and will force it to pull the latest updates. Careful! that will also delete any connection settings that you might have used for manual configuration instead of automatic configuration.
Finally, try establishing an IM conversation first and adding Audio to that running session. That has proven to be most effective when clients refused to request bw from CAC. After that also non IM initiated sessions request BW.
If you still can't see anything happening on the monitor or requests in the log files I suggest you have a closer look at your Edge and Front End Servers. Make sure all services are running and restart the Lync Bandwidth related services.