Unable to use windows 8 on external drive with bootcamp?

I have Windows 8 installed on a external drive with bootcamp.
And I wanted to try out Parallels, so I let the program use the windows that is on bootcamp.

But after a short while it can't bootup or shutdown.
It can't find the hard drive to boot from and when trying to shutdown it says something about ntfs.

And now I can't even start up Parallels due to some reason... =/


iMac 27" late 2012
3,4Ghz i7
32Gb
Os X Yosemite 10.10 - 500Gb Samsung SSD (external thunderbolt)
Windows 8 Bootcamp - 500Gb Samsung SSD (external thunderbolt)

*edit*

Fixed it after a few tries..

 

What did you do? Can you explain?

Thanks in advance