Hello ladies and gents,
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.
Cheers!
Jeffrey