Gameboy Color Cheats

I keep putting in cheats and it says incorrect code, What am I doing wrong, how should the codes be written in for it to count as correct, I am making sure it is gameshark codes, am I putting in the master code wrong maybe? I just need a "how to correctly put in codes" example, lol.

Btw, I did read the "cheats, how to use" article.

A lot of the cheats do not work for some reason. If you followed the guide and entered the master code, then the code afterwards and it did not work, I would email the developer and see if he can assist you.

Good luck.