So... after a loooooooot, and I really mean a looooooot of testing and debugging, even decompiling the device build in apps. I manage to make it work!!!!!
Basically, the idea is to upload your app and your dlls (without any of symbol libs) into the root of the Application section of the device. Even creating a folder within the Application section don't work, it has to be at the root of Applications.
That and make sure that the OS is upgraded and you are working with the latest sdk.
This is an old thread but I really hope that it helps someone.