fix errors.

I don't think this sample can work since printToLog is not defined and it has typo mistakes.
and Here's my question:

1, Why register the listener in ondomready? why not in deviceready event handler  or bind events function ?
2, After invoked, do I need to call bb.pushScreen() to set up the display screen ?
3, If I invoke my app as a card, can I swipe right to back to the parent document without change anything on screen ? 

after tried for about 1 hour I still can't get the code run. when I call blackberry.invoke.invoke(request,func,func) it tolds me successfully invoked but I never get it in "invoked" event,the event never fired.
I don't know why.