So I changed a few of the .png files in my googlevoice.apk. After doing so, when I try to install it says installation failed. I tried to install via ADB and got "install parse failed no certificates" However, I was able to copy the .apk into /system/app and it worked fine. I am curious, because this was the same .apk that was previously installed, and I didnt know that changing the .png would cause a program not to install. Any information or help would be greatly appreciated!