Problem with slider in directory press

Hi every one, I am having problems with having the right slider I want for my website. In the display settings there is about 8 slider options to choose from and only 2 work the 695px by 265px and the 695px by 300px. I want to use the option 960px by 360px but it doesn’t work, the images are just set on top of each other and I can see when using firebug that there is no code for a slider there… Why are these options showed if they don’t work? I’d be most greatful if anyone could help?