Im new to this

I decided to start picking, as I have always been interested in puzzles, and saw this as the next step!
I have managed to pick every padlock i have found,(with the exception of a shrouded yale 'level 7' security padlock)
I have now moved onto better things, away from padlocks. I have purchased some door locks:
Union Turn 5 pin Cylinder - Euro Thumbturn cylinder
The funny thing is, that at first they seem easy to pick, one or two simple rakes and the barrel spins. However i have now realised that it actually isnt getting the job done. The part in the middle (appologies for lack of vocab) that actually spins whtn the key is inserted, does not spin upon picking.
to summarise:
I can pick the lock, by raking
the barrel spins, to 180 (i then have to re-rake, after reading the forums here

the barrel spins all the way round to 360, but the actually un-locking mechanism, is never engaged...
what am I doing wrong!?!?
Many thanks, and i look forward to posing lots more

Buzz