I took the jetty to the island, walked slowly up road to the castle doors with Serana and waited for her to give me the "When we get in there....." speech but still unable to obtain entry. I've tried waiting 24 hours, fast traveling to other locations and returning days later, and even loaded an earlier save when I was level 42 (now level 45) and going through the entire quest again where I find/meet Serana and still cant enter. Could it be due to the fact that I am also a werewolf?
Any help, tips, advice is greatly appreciated.
Again, I tried all of the following with no luck:
Waiting 24 hrs
Fast traveling away
Reloading earlier save (3 levels below)
Going through the quest to rescue Serana again