tomcat6-installation auf Ubuntu12.04

Will ich installieren tomcat6 auf meinem ubuntu server, aber ich bin immer Fehler wenn ich sage
sudo apt-get install tomcat6. Wenn ich install tomcat7 kann ich erfolgreich installieren.
Aber ich bekomme diese Fehlermeldung während der Installation von tomcat6,

    ubuntu@ip-10-202-47-144:/var/solr$ sudo apt-get install tomcat6
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
 tomcat6 : Depends: tomcat6-common (>= 6.0.35-1ubuntu3.2) but it is not going to be installed
E: Unable to correct problems, you have held broken packages.

Irgendwelche Ideen ?