Can't mount Seagate Thunderbolt disk

I have just gotten my new Macbook Pro 15" Retina (Late 2013) - the biggest model with 512GB harddrive.

I'm a professional photographer and I have been using a Seagate 3TB Backup Plus harddrive and a Seagate Thunderbolt bay. Previously I have used the setup on an iMac 2011 and it had worked perfectly.

So when I connect the drive on my new Macbook Pro it won't mount... if I use the USB3 bay instead it works fine, so it seems to be a Thunderbolt problem.

So any suggestions?

Kinda need to solve this pretty fast, so I can get my workstation going.

See the two attached images.