Upgrade to testing

[komodo@uvt.cz]

Hi
I have installed stable and i have to change to testing but i always get
this error

sysresccd:/# aptitude install mysql-server
Reading package lists... Done
Building dependency tree
Reading state information... Done
Reading extended state information
Initializing package states... Done
Reading task descriptions... Done
The following packages are BROKEN:
  mysql-server
0 packages upgraded, 1 newly installed, 0 to remove and 0 not upgraded.
Need to get 88.2kB of archives. After unpacking 123kB will be used.
The following packages have unmet dependencies:
  mysql-server: Depends: mysql-server-5.1 which is a virtual package.
Unable to resolve dependencies!  Giving up...
The following packages are BROKEN:
  mysql-server
0 packages upgraded, 1 newly installed, 0 to remove and 0 not upgraded.
Need to get 88.2kB of archives. After unpacking 123kB will be used.
aptitude failed to find a solution to these dependencies.  You can solve
them yourself by hand or type 'n' to quit.
The following packages have unmet dependencies:
  mysql-server: Depends: mysql-server-5.1 which is a virtual package.
Resolve these dependencies by hand? [N/+/-/_/:/?]
Abort.


Please, where is the problem ?

I want to install 64bit but this is the problem that i get.

Thanks

Martin