My bonus levels dont work?

Help please, finished 10 levels with 3 stars and bonus level not working?

Please would someone expound on this. I have finished the game on normal, but not yet with all 3 star levels and no sign of bonus levels. Where and what are bonus levels?

Please someone tell us where they are hiding... Thank you.

has to be 3 stars on all the levels leading up to the bonus...hover over the bonus button and it will tell you this...if one of your levels does not have a star on it, it is not 3 stars and you will have to get that level up to 3 stars to access the bonus...hope this helps