An exception when creating CompatibleRenderTarget from DcRenderTarget

I’m using the .Net Direct2D API in “Windows API Code Pack for .NET” to improve the drawing performance, it always throws the “Exception from HRESULT: 0x88982F80” when creating the CompatibleRenderTarget from DcRenderTarget, I don’t know why, it has been troubled me for two days. And here is my code:

var renderTarget = dcRenderTarget.CreateCompatibleRenderTarget(CompatibleRenderTargetOptions.None, new PixelFormat(Format.R8G8B8A8UNorm, AlphaMode.Straight), new size);

It works fine if I change the “AlphaMode” to others, such as “Ignore”, but it’s unable to make the renderTarget transparent, or gives a bad drawing quality.

Hope anybody knows the reason or please be free to post your ideas.

Regards!

Thanks,