After smooth with wizard create application on ccx 5.0(2) everything was going well except thing that I can have only one call at queue. For next call I get busy signal until call in queue was terminate or answered.
You need a bigger port pool (group). I haven't played with UCCX for a while, but with IPIVR you had to configure both the number of ports and the size of the Media Control Group.
Check your settings.
Maybe you have one configured to match the number of ports you want - probably up to your licence - (corresponding to the number of concurrent calls in the IVR getting treatment or in queue) but not the other. Easy mistake to make back then.