Might want to see this post.
[Link: remotecentral.com]Also, be aware that you must create a button with a Jump Action and then set a ProntoScript name for the button. You then, using ProntoScript, retrieve a reference to the widget and then call executeActions() on said widget.
If you use the same search I suggested in the linked thread above with timeframe of last 2 years, this thread should be the #1 hit.
[Link: remotecentral.com]May I also suggest reading the ProntoScript FAQ on the Philips site as this thread contains a direct quote from the FAQ. There is other stuff in the FAQ that you will want to be aware of as well.
Good luck with your scripting. :)