I installed it under Mandrake 9.1 and ran into the same problem. Then I decided to try and run it as root and it worked... however, i'm not a fan at running things as root and anyway, was not able to get much further with configuring Ardour to work with my cards (I have two soundcards... M-Audio Audiophile 2496 and SB Audigy Platinum)... Anyone had any luck with two soundcards? I use my SB mainly for soundfonts and everyday usage, and my m-audio for the spdif and analogue inputs.
Have you tried running it as root? If that solves your problem, you'll know it is a problem with permissions (and I'm a newbie as well, so not sure as to the best solution). Would it be to add that prog to a list for sudoers and add your account to it? Not sure. Anyone?