ok, I fixed the problem.
for those who could get the same:
the empeg amp remote wire (the 2 blue wires going to the ISO connector) are pluged in a slot. In the corresponding VW ISO connector slot, a constant 12v red wire is pluged (e.g. for VW GPS install), and that's resulting a power overload for this pin. By luck it didn't blown something, but it might...
What I did is I just disconnected the 2 blue wires pin from the empeg ISO connector, and islolated it. And now everything works fine.
So, why the amp remote (& power antena) wire is connected back to the ISO connector???