I have more data about the problem. If I run the app, without opening the photo hub, works well. If I open it fails.
Both by entering the hub directly or execute before PhotoChooserTask or CameraCaptureTask.
This I have observed on the emulator (I have no WP8) but when I test in a real one, using Nokia RDA, fails from the begin, but perhaps because someone has already opened the photo hub before I use it