First off, the animation is great. Kinda reminds me of Mel-O-Toons.
Second off the music needs some work.
However it's not your singing voice. You sing just fine, but the background melody is not quite in tune with the song as in it's not consistent. Comes across as you trying to play the song to the voice, when you should be singing your voice to the song. But all and all a great short film, very amusing and you should post this on youtube, you may gain a cult following for this.