Bootcamp: Insert Boot disk error

Ok so I have been trying all day using all sorts of ISO's that I can find but I run through the process in Boot Camp Assistant ensuring that all three options are selected and I point to my ISO but after the system restarts I just get the "No bootable device" error.

I can access my OSX partition by holding alt/option at startup, Windows also appears here but selecting it just results in the same "No bootable device" error.

I have a mid 2011 mac mini (no cd/dvd drive), OSX Yosemite. I had no issue with Mavericks.

All help appreciated...