Java Problems

Well, i like to play a game called Runescape and its been working fine on Safari for the whole time i've had my Macbook. Runescape requires Java but suddenly when i tried downloading the latest Java update on my Macbook, Runescape doesn't work anymore and an error says that I dont have Java installed on my computer.

I have firefox also on my Mac and Runescape works just fine on it. I have Java boxes enabled in the Safari preferences and stuff. Any Ideas why stuff doesn't work?

 

I think i kno how to do that, just to be sure can u give me instructions for doing that