3.5.13 - krun-dialog error

Hi all, running on Funtoo/Gentoo i have this strange problem with the ALT+F2 run-dialog in trinity-3.5.13. Hitting ALT+F2 i can run stuff like firefox htop xchat ... but other tools like top urxvt ... i get an error saying 'Could not run the specified command" Even weirder as i said i can run "firefox" but "/usr/bin/firefox" gives me the same error as above... Using "Options-> Run in Terminal Window" it works too but i get an additional konsole-window. I'm wondering if i could be missing a kioslave or sth. kdebase-kioslaves is installed.. i think it is not a path problem because all tools are located in /usr/bin/ and the absolute-path doesn't work too. Is there sth. else that i should be looking for? How can i get the debug output from that dialog? greetings, Roman