Actionscript 3.0 & Flash

I'm currently developing a memory game which is almost 80% done. But I need to make some improvements like separate themes, different difficulty levels, effects such as transitions(fade in/fade out or zoom in/zoom out. There's a problem with my shuffling of cards, where the randomise of card images are picked randomly from a folder, but for example if the number randomise is 2, it will pick images from 2 onwards (2,3,4,5,6,7,8), and not in randomly order (2,5,10,7,8). I hope you can assist in solving this problem. There's is a game that I want to develop similar to it. You can visit the game at [login to view URL] and play the game Match It. Where in the expert difficulty, it will rotate the cards after a period of time. Ideas are welcome to improve the flash games