Fedora 14α not compositing

[Petrus de Calguarium]

I installed F14α to a spare partition using the KDE live CD. All went well, but I am 
unable to enable Desktop Effects.

I have tried setting setting functionality checks both on and off, to no avail. A 
message stating:

"Desktop effects are not available on this system due to the following technical 
issues:"

always appears on the effects configuration page in systemsettings, but no reason is 
given. When I try to resume compositing, either with the button or with shift-alt-f12, a 
notification message states that another application has disabled desktop effects, but 
there never is mention of which application, nor why.

I should also mention that the "All Effects" page listing of available effects is 
completely blank.

I have exactly the same setup in f13 and all works just fine, but the same programs 
installed in f14α don't work.