WD My Book Thunderbolt Duo 8TB

I’m having an issue with hooking it up with my MacBook Pro. Normally I have no issues with it, but it just happened that my computer doesn’t detect the drive anymore.

When I just plug the power cord into the HD and not the Thunderbolt cable to the MacBook, the harddisk runs on its own. Usually, that only happens when I connect the Thunderbolt cable to the computer.

Any help on this?