It's taking a huff and won't let me click it anymore.
I'm using amarok 1.4 with kubuntu 8-kde3. I recently had to re-install everything and I'm not certain that it's been working since the reinstall.
I think it was but in any event I only noticed it was greyed out after I'd spent an hour getting moodbar working.

any ideas?

Works in 2.0. For Amarok 1.x it's impossible to fix.