Why am I not seeing a loading screen in my application on OS 3.1, but I am on 4.0?

I have a loading screen that appears when my applicat开发者_C百科ion loads on an iPhone 3G running OS 4.0, but not on an iPhone 3G S running 3.1.2. What could be causing this?

So, the missing link was that the loading-screen has to be named Default.png. it is NOT enough, that you have the file in the info.plist - or it is just enough for a 3g maybe.