There's a bug in 1.8.3 and below that breaks web services for walled garden sites. It was fixed in 1.8.4, so if you haven't upgraded yet and are on a walled garden site, upgrade and see if it fixes your problem.

Ok thanks it work fine :) Now I will try to use authentification with web service any idea how I start? I read the documentation and it's not sufficient for beginner.

Is a simple view if I put it in widget it work but in lightbox (I used thickbox) the elgg variable and functions are disabled.

I tried add_to_river() but no result. Brett have you a simple Hello world plugin tutorial for 1.8.3? not the widget. I need a plugin toturial that display view and for exemple make change to the river.

I'll need to see code to understand what you mean about the lightbox. Elgg has a built in lightbox so you shouldn't have to include your own.

What does your add_to_river() code look like? Have you looked at the bookmark's plugin?

Ok tomorrow I will send you the code but I have make a link in the hello world widget (in the setting) when you click on it a light box appear and open an other file let's said map.php in this file I show the google map but I need to get the user id and other elgg functions but any one of them work maybe a simple elgg_echo.

All the existed plugin does not have a clear code. I need a simple exemple only for the river for exemple a hello world plugin. I used add_to_river like is mentionned in this page http://docs.elgg.org/wiki/River