I have one of the newer A5's and have experienced exactly what you've described. It happened to me right out the gate, the first time I took it out to the range to shoot it.
I'll second what CP said about pushing down the spring loaded clip to release the next shell in the magazine tube. I've had to do this plenty of times, especially when I had an issue with the bolt lock in front of the trigger.
It seems to me that my A5 is just "picky" about what shells it likes and doesn't like to cycle. For instance, I do a lot of target shooting throughout the entire year, and for whatever reason my A5 will not cycle Rio shells. But on the other hand, it's never had any problems with Gun Clubs (which is fine by me, because they're great for reloading).
I don't know what actually causes the cycling issue to happen, but I found that by shooting different shells I was able to figure out which shells cycled and which ones didn't. The crappy thing, is that the shells that cycled tended to be the more expensive ones.