I hear were wolf and vampires cancel each other out? is that true?

now i heard of likens...the vampire/warewolf.... now i know that the tv exaderates and all, but the reality answer that i seek, is - is it true vampires and were wolfs can not exist as one? i know of psyc vamps, and were wolfs and past lifes... but what about being a rare hybrid/ mix breed? that queshtion had been bothering me, can some one tell me the truth of all this? thanks.