Sometimes we post and then we realize where the problem is and the post becomes useless - happens to me too
Anyway...
I have 2 virtual drives: in the 1st one I've put the CoH image and validate the media. after validate (that was easy) I swap images and then put the CoH:OF image (the long part).
Note: the 1st drive may not be the 1st in DT list. Use the letters.