Bootcamping to windows 8 pro - no drives found?

I have been trying to bootcamp to windows 8 for some time now, but I keep running into the same problem. I'm using an external disc drive to read the installation disc. When the Bootcamp Assistant restarts the computer, a black screen appears saying <Press any key>, not sure if that affects anything. If I dont press anything it boots back to mac and I have to redo everything. When I do press a key however, it starts the installing process and everything is good until this step after you agree the license. It wonders "Where do you want to install Windows?".

(sorry for the bad quality, its taken from my phone)

In all guides from this point you choose bootcamp drive and format and so on. But for me no hard drives what so ever appear. Loading drives doesnt help either. I cant find any sollution to this and I dont know whats causing the problem. I think it maybe have to do with the <Press any key> screen but Im not sure of anything. I have googled this and checked all the guides but I cant find anything. When I go back to macintosh I have the bootcamp harddrive nad the macintosh harddrive,

so why doesnt either of them show up?

Specs:

iMac(late 2013)

external disc drive plugged in via USB port

windows 8 pro installation disc

If you need some other specific information ask. Would be so thankful for any kind of help 🙂.