[android_rpc] RPC blocked on upload

I cannot run tests/android_rpc_test.py, the script blocks on line 71:
remote.upload(path_dso_cpu)

I have check the availablity of the device before and also that the key used in the script is the same that the one used by the tracker.
I have recompiled at least three times during the day, nothing changed.
Any idea on where the problem could come from would be really appreciated.
Thanks.