I recently tried to install pd-extended on my linux mint 11 machine (ubuntu 11.04), and when I try to start pd-extended, it doesnt start. When run in the terminal it spits out

/usr/lib/pd-extended/bin/pd-gui: error while loading shared libraries: libtk8.5.so.0: cannot open shared object file: No such file or directory

Running

sudo pdextended

does the same thing.
Can anyone help me? I need to use pd for a school project...

tcl and tk are apparently already installed and at the current version