I'm developing an iPad application. I have been provided with a PNG image that contains some transparency - basically a drop shadow. The problem I'm having is that this is rendering poorly within the application, both on the device and in the sim.

I can't provide the whole image but I've made up some samples to illustrate. The first is how the image appears in the PSD (correctly that is). The second is how it appears on the device. You can see that the strip of shadow in the middle of the image is distinctly more yellow and poorly looking.

Any ideas what I'm doing wrong?