The script was really cheesy and the directors/producers/screenwriters were running out of ideas. Also, the ratings were extremely poor. Therefore, it had few views compared to other Nick shows like Victorious, BTR, and HOA, so not many companies wanted to buy commercials. So, the whole show made less money and everyone wanted to make money, but not much was made.
But I still think the show was really good. Yes, it was cheesy, but it's quality is much better and non-compareable to Disney shows.
Yeah... I don't know why they have cancelled it.. Most people said because the ratings were poor, but I think the ratings of How to Rock are like, 1,000,000,000%, so it's pretty good...