I guess it's because the CUMA cannot reach the "proxy host name" you configured (in your case, that was "proxy.cuma")
Officially, that name should be the FQDN or IP address of the ASA outside interface.
If you *just* want to start the service, the "proxy host name" can be any reachable IP or FQDN.
Michael
http://htluo.blogspot.com