Sweeper not working

Hello,

I have a strange problem with sweepers:

1) When I try to put the loading of the sweeper in the config.observe
section it fails because the used plugins for the observed model is
not found (Bug?)

2) When I add it manually after the config (MySweeper.instance) it
works only once?!
  This means after the second request where a sweeper should trigger
nothing is called

3) When I put it in application.rb before filter and call
MySweeper.instance it works all the time.

BUT:

With lighttpd it works not at all?!

Any hints on that?

Regards
Till