Upgrade from 10.10 to 11.04 fails because of isc-dhcp-client

When trying to upgrade from Ubuntu 10.10 to 11.04 update-manager fails with the following message:

An unresolvable problem occurred while calculating the upgrade:
E:Error, pkgProblemResolver::Resolve generated breaks, this may be caused by held packages.

I'm attaching files from '/var/log/dist-upgrade/'.

I don't get any output from the command 'dpkg --get-selections | grep hold'.

A dist-upgrade from the terminal gives me the following output:

$ sudo apt-get dist-upgrade
Reading package lists... Done
Building dependency tree
Reading state information... Done
Calculating upgrade... Failed
The following packages have unmet dependencies:
 isc-dhcp-client : Breaks: network-manager (< 0.8.2~rc1) but 0.8.1+git.20100810t184654.ab580f4-0ubuntu2.1 is to be installed
E: Error, pkgProblemResolver::Resolve generated breaks, this may be caused by held packages.

And 'apt-cache policy':

apt-cache policy isc-dhcp-client network-manager
isc-dhcp-client:
  Installed: (none)
  Candidate: 4.1.1-P1-15ubuntu9.1
  Version table:
     4.1.1-P1-15ubuntu9.1 0
        500 http://es.archive.ubuntu.com/ubuntu/ natty-updates/main amd64 Packages
        500 http://security.ubuntu.com/ubuntu/ natty-security/main amd64 Packages
     4.1.1-P1-15ubuntu9 0
        500 http://es.archive.ubuntu.com/ubuntu/ natty/main amd64 Packages
network-manager:
  Installed: 0.8.1+git.20100810t184654.ab580f4-0ubuntu2.1
  Candidate: 0.8.4~git.20110319t175609.d14809b-0ubuntu3
  Version table:
     0.8.4~git.20110319t175609.d14809b-0ubuntu3 0
        500 http://es.archive.ubuntu.com/ubuntu/ natty/main amd64 Packages
 *** 0.8.1+git.20100810t184654.ab580f4-0ubuntu2.1 0
        100 /var/lib/dpkg/status

The package version is update-manager 1:0.142.23.