#3 installing this jar disables auto activa

[Anonymous]

when I tried installing param-guess.jar in jdt-ui plugin,
modified the plugin.xml and restarted the Eclipse, the auto
activation refused to work. When I have "fill argument
names on method completion" disabled, everything works
fine (i.e. auto activation works) but when I enable it, even
the auto-activation fails to work.
Am I missing something here or is it a bug ?