Can't cast abilities as Vel'Koz

I've just played a 5v5 game as Archlight Vel'Koz, and I couldn't cast any ability. I had Skype in the background, but I closed it and it didn't change a thing. I started from the red side of the Rift, and bought Spellthief's Edge, two health pots and a ward, plus the yellow trinket. I tried to see if it would change after level 2 but it didn't, so I disconnected and reconnected. It worked afterwards.