Hi Nina
The answer to your question is "it all depends!" It depends upon your intention. Sarah Powers tells of the time, before she understood the benefits of Yin Yoga, when she used to come to Paul Grilley's Yin classes right after doing a nice, sweaty Ashtanga practice. It was great of course, but later on she realized that by warming up her muscles first, she was not getting the most benefit for her yin tissues with this sequencing. She then switched them around. Do yin before yang, if your intention is to get the most benefit physiologically for your tissues.
There is a chapter in my online version of YinSights where I talk to this point: visit this link
http://www.yinyoga.com/ys2_1.1.1_cold-warm_muscles.php.
Now, if your intention is to chill, relax or mellow out after a dynamic yang practice, then doing Yin Yoga second is perfect. You won't get the most physical benefits, but you will get the mental and emotional benefits.
So, it all depends.
Hope this helps.
Bernie