Hi Alberto,
We ran into this exact problem in the lab when first building UC. This was our problem (naming convention). Once the prefix names matched up everything came to life right away!
On the Cisco Voice Mail Server page, the name of the voice mail server appears. We recommend that you accept the default name for the voice mail server. If you must use a different name, however, the name must have no more than nine characters.
The voice mail server name must match the Device Name Prefix field in Cisco Unity Connection on the Port Group Basics page for the voice messaging ports.
Device Name Prefix
***Enter the prefix that Cisco Unified CM adds to the device name for voice ports. This prefix must match the prefix used by Cisco Unified CM.
For example the prefix might be UVM1- XXXX this must match in both CCM and UC.
http://www1.cisco.com/en/US/docs/voice_ip_comm/connection/7x/integration/cucm_sccp/guide/cucintcucmskinny050.html
Hope this helps!
Rob