I think I see what is happening here. Net::Appliance::Session uses a phrasebook to both match the command prompts on different devices, and send commands to the device.
The phrasebook is in the Net::Appliance::Phrasebook module (you will have this installed already), in a file called nas-pb.yml:
What I think happens is that the "admin:" prompt (that's the command line prompt after you log in?) is not matching the regular expression in nas-pb.yml. What you can do is create a new phrasebook according to the documentation in Net::Appliance::Session and Net::Appliance::Phrasebook which matches this prompt. In fact, just changing the prompt value in the current file to have [#>:] instead of [#>] will probably do.
One other thing is you will probably want to disable paging, if the UC command line doesn't use typical Cisco --more-- style paging. Do this using $s->do_paging(0) before calling $c->connect().
I hope that helps, but let me know if you still have a problem getting it working. This is new territory for the module!