Hmm well maybe this is... how you are? XD I don't know what to advice, maybe different styles come to us easier at different points in life...
Maybe this really is a type of music you have an aptitude for though, even if it's not you at all, may not be a bad thing. Personally I feel like dark music actually helps you through darker times better than brighter music does, it's therapeutic, so it's not like an inability to make bright music means the music doesn't still brighten your day, in a way...
Or in the end maybe practice makes perfect after all; you just gotta keep trying. :)
Good luck though; hope you get some more professional tips in that forum!
Yatsufusa
I severely lack understanding in the whole music creation process - but I 'do' know that your peers would probably be happy to help you if you asked them somewhere with more visibility. You should try the Newgrounds Audio Forum:
https://www.newgrounds.com/bbs/forum/13
FantasistEldrun
thank you