The value n always starts at zero, so the parameters should be passed as image0, image1, image2 and so on. Be careful with the capitalization of the mixer names. If you get the cases of the letters wrong, they will not work. If no mixers are specified, all mixers will be used. I'd suggest you put the .jar file in the same directory as the page on which it will appear.
Some web browsers have trouble opening applets straight from a hard disk.
I have noticed this happen with Internet Explorer 3 and Netscape 4. This is an applet, it is intended for use within web pages. You can't open it directly. If you try, it won't harm your computer, but neither will it show you the applet. This is a very common problem.