Low end kit - Campag Question I

[GrumpyGregry]

Any reason why a three year old Veloce triple shifter and mech, currently shifting on a Campag race triple chainset with a Campag Veloce square taper BB, won't work with a 2012/13 Campag Centaur Triple chainset (same chain ring sizes) running on a Campag Power torque BB?

Purpose of thread is not to discuss the relative merits of Campag v SRAM v Shimano so please try to stick to subject....