That’s because you had a duplicate connection to the network - That’s not allowed (CoC A8):
A8 An account holder shall only make one connection to the VATSIM network during any given session, except as may be otherwise provided for in this Code of Conduct.
.towerview on vPilot is the correct way to do it, but only works if you have an active controller connection on Euroscope. Observer connections on Euroscope won’t work