Hopefully by now you have solved the problem. I received this issue when I first connection my phone into one of my four usb ports on my computer. I would open the phone's folder system and see nothing. I just tried a different usb port, and this time I touched/opened my phone while it was plugged in. It asks me if I want to establish a MTP connection, and I show yes. KERSHAZAM! The phone's data connection is now set, and I can transfer video and audio.
I recently had the same problem. I eventually discovered that the usb lead will fit into the A5 either way round, but will only transmit data one way round. So they seem to have used a phone lead that does not appear to be handed, but actually is handed. Where is the sense in that?
I did all that and it still didn't work so I dug out the original white charging cable that came with the phone and connected that. When it still didn't recognize the phone I rebooted while the cable was connected and voila! it worked. I was still had it set on MTP connection though not PTP."
