Windows Phone 8 tile confusion

When you export a Windows Phone project out of unity, you can see that unity creates some default tiles for you. The problem is that I when tried putting my own tiles into the project via the WMAppManifest.xml file interface, they showed up blank!

Note: I would like to use the "iconic style" tiles.

After some testing I figured out that the problem is that my icons are fully rendered images, meaning, there's no transparency in the image. Here's an example:

That image will show up as blank because it has no alpha.

So it seems as Windows Phone will only read the alpha in your tiles, rather than the colors of the actual images?

What if you would like to turn that off and have them render normally or fill up the entire tile for that matter?

Can I customize this stuff or am I stuck with a simple white icon to represent my game?