Cannot change XBMC Icon

Hi everyone..!

I have an Apple TV 2, running tethered-jailbreaked iOS 5.2.1 on it. I installed XBMC 12.2 via command line (not via "NitoTV" or "aTV flash"). Everything runs fine, the icon appears on the main screen and I should be happy..! ;-)) After that, I installed "NitoTV" and "aTV flash" on my Apple TV. Finally I wanted to change the XBMC icon to suit to the rest of the icons. Somewhere on the web I found a quite nice one, downloaded it and put on my Apple TV...but the icon won't change. I restarted Lowtide each time of course.

Here is what I tried:
- Replaced "AppIcon.png" in folder "/private/var/stash/Applications/XBMC.frappliance"
- Replaced "TopRowIcon.png" in folder "/private/var/stash/Applications/XBMC.frappliance"
- Replaced "com.apple.frontrow.appliance.xbmc@720p.png" in folder "/private/var/stash/Applications/AppleTV.app"

The size of my logo should be correct: 187x108 pixel, color is RGB, saved as PNG.

Even when I rename all 3 files, the original XBMC icon is displayed correctly on the main screen.

Another strange thing I noticed: When I try to open "com.apple.frontrow.appliance.xbmc@720p.png" in Photoshop CS6, it gives me a "rendering error" (it's hard to translate german errors). Is this PNG somehow protected..?

Any ideas what goes wrong here..?

Thanks in advance,
John