xfce4 can't be installed because of broken packages/dependencies

I tried to install xfce4 (apt-get install xfce4) but it doesn't install because of broken packages. My OS version is NCP2 Beta2. I did apt-get update before I started to install any packages.

The following packages have unmet dependencies:
  xfce4: Depends: thunar (>= 0.8.0) but it is not going to be installed
         Depends: xfdesktop4 (>= 4.4.2) but it is not going to be installed
E: Broken packages

When I try to track down the dependencies I get this:

$ sudo apt-get install thunar xfdesktop4

The following packages have unmet dependencies:
  thunar: Depends: libthunar-vfs-1-2 (>= 0.9.0) but it is not going to be installed
  xfdesktop4: Depends: libthunar-vfs-1-2 (>= 0.9.0) but it is not going to be installed
E: Broken packages

$ sudo apt-get install libthunar-vfs-1-2

The following packages have unmet dependencies:
  libthunar-vfs-1-2: Depends: libgamin0 but it is not installable
E: Broken packages

And finally

$ sudo apt-get install libgamin0
Reading package lists... Done
Building dependency tree
Reading state information... Done
Package libgamin0 is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source
E: Package libgamin0 has no installation candidate

$ sudo aptitude search libgamin0
Which gives nothing so there is no libgamin0 package in the repository.