RDPSession could not work in Windows Service app

Question

I have a desktop sharing WinForm application using RDPSession, it works well and client app can connect it via AxRDPViewer.

But after I change the sharing application type to Windows Service, the client app can only see a black screen of the sharer, like this screen shot

So I want to know if RDPSession can work in a Windows Service app ? Any suggestions?

Thanks for your comments.