I have observed a4j:commandButton works only on Page Refresh

Here is the situation

I am using two h:selectManyListbox to moves Roles i.e. All Roles to selected Roles using <h:commandButton value="--&gt;" />

h:commandButton works perfectly fine , the only limitation is after moving the value from left to right Listbox, whole page is automatically refreshed & the cursor moves to the top of the page

This is where we thought ajax4jsf would come in handy & started using
a4j:commandButton instead of h:commandButton.
The result is when we click the a4j:commandButton it doesnt moves the value from left to right Listbox. Then we did page refreshed then only the value moved from left to right ListBox. Quite Amazing !!!. This is totally opposite to behaviour of ajax

We want a4j:commandButton to move the values from left to right ListBox without page refresh . Any pointers/suggestions will be highly appreciated