TV animation from the 2000’s

Hi everyone. I hope someone can help me find this TV show I used to watch as a child. It used to be broadcasted on Boomerang here in Brazil and it’s been years of me trying to remember the name or find something online based on whatever I can recall from it, but with no luck, maybe one of you can help. It was an animated show, the location was this hunted castle that the main character, who was a vampire I believe, moved into. There were a bunch of other characters that lived there too but the one I can remember the most was “Sad”. I don’t know if that was her real name but what I can remember was that this character would always be crying. In an episode she participated in some talent show but the twist was that she was only a good singer when she was sleeping. And that is basically all I can remember. I watched this show up to 2010 I believe but I can’t say for sure when it was created. It’s not a lot but maybe someone will remember...