[fusion-dev] Custom widget problem

[web]

Hi everybody,
I have a widget that works with the previous version of mapguide, but with the last beta version an error occurs when the site is loading:

Fusion Error: 
WARNING: Exception occurred in AJAX callback.
widget.paramRegister is undefined
Location: undefined (49896))

in FusionSF.js

It seems to be a problem of initialization of my widget, do I need to change something to my widget so that it can work with the beta version of mapguide?