You need to clean your build directory whenever you change resources (i.e. add new images, delete old images). It makes the build take a bit longer but you'll

You need to clean your build directory whenever you change resources (i.e. add new images, delete old images). It makes the build take a bit longer but you'll have no issues. So i.e. just delete the contents of the Resources/build/iphone directory and then rebuild the app from Titanium.