When I name one net and name another one with the same name they get connected (very useful stuff) BUT when I rename one of this net (to unconnect it) then the whole design get affected by this small change!
It means that if I name one net VCC,another one VCC and I realise I made a mistake and connected VCC instead of GND. I correct the mistake by changing the name of the net => suprise, I just created a big short circuit!!!!