WP7 consume a WCF Service

I have a WCF web service deployed on azure. When I consume it using WCFClientTest, I successfully get return data after invoking my methods. But when I try to consume it through WP7... it returns nulls (collections of objects are expected, either empty or filled with objects of course).

I've read over the internet that lot of开发者_如何学编程 people had such problems, but couldn't find a straight fix to this, I restarted Visual Studio to get rid of the well known warning related to the web service reference while developing for WP7 but it didn't help at all, and my code has no warnings left.

I guess it's a problem with serialization or maybe security... I really don't know

Did anybody run across such an issue already ? Any directions to solve it ?

PS: I deploy on emulator

Edit:

In order to back up my question, I'd like to let you know that I've just tried using a method that returns a simple string and this works. So the problem is with collections.