Scheduler callback error.

I just upgraded from 4.6 to 5.0.

Everything went fine, except for callbacks.

Anytime, I try to fire a callback:

ProvisionCalendar.refreshCallBack(new Date(), null, 3);

I get the following error: 'An exception was thrown in the server-side event handler:'.

However, control never reaches my server side event handler.

Something else is going wrong.

Any ideas?