FileStream in IPhone.

Can anyone tell me why I get "Unity Iphone has exited with status 1" if I use `var fs : FileStream = new FileStream("/xxx.xml",FileMode.Open);` ?

Correct me if I'm wrong, but I think I heard somewhere that it's the file handling system of the iPhone which prevents you from accessing files like you can on a computer. Still, I don't use Unity iPhone, so I'm probably wrong.