Download Free Java Software http://www.adobe.com/shockwave/downl...ShockwaveFlash
More than likely you need to download and install java and flash. Most online games require one or the other to play (usually flash).
If you have installed both, try using a different browser. Some admin restrictions we have here at work keep us from seeing embedded flash or java, but if we switch to internet exploder they work just fine.
You might also want to make sure that java is allowed in your browser. It can be found under Tools/Options/Content in most browsers.
That's all I can think of off the top of my head.