So I have a DrawingSurfaceBackgroundGrid inside of a PhoneApplicationPage, in my WP8 app; and I would like to take a screenshot. As far as I can tell (from google), there isn't a call to simply "take a screenshot". What people are doing is using a WriteableBitmap, like this:

```
WriteableBitmap wbmp = new WriteableBitmap(test, null);
wbmp.SaveJpeg(isoStream2, wbmp.PixelWidth, wbmp.PixelHeight, 0, 100);

```

I have tried test as both the DrawingSurfaceBackgroundGrid, and the PhoneApplicationPage. Neither of these are working for me. Could it have something to do with the fact that I am rendering everything using RenderTargets and pixel shaders (in SharpDX)? I just get a black image. Here is the code to save the image:

```
IsolatedStorageFile isoStore = IsolatedStorageFile.GetUserStoreForApplication();

using (IsolatedStorageFileStream isoStream2 = new IsolatedStorageFileStream("new.jpg", FileMode.OpenOrCreate, isoStore))
{
    WriteableBitmap wbmp = new WriteableBitmap(test, null);
    wbmp.SaveJpeg(isoStream2, wbmp.PixelWidth, wbmp.PixelHeight, 0, 100);
}

```

But like I said, it just creates a black image. 

Any ideas?