PocketMatrix

I think I start knowing the problem I have, I think that it's a privilege problem, due that my application is not signed.
Could that be possible?

Also, does anyone can shed some light on smartphone code signing? I have an unlocked phone and I can execute my apps, however I get a warning telling me that the application is not trusted, and asking to execute.
But what would happen if the phone were not unlocked? I'd get the same warning? or it's just that unsigned apps can't be executed in any way?

TIA
Kak