What happens when you key-in mdl load WPFSample.dll? What messages do you see?
[quote user="m gao"]I got the addin loader ma files (under C:\Users\{username}\AppData\Local\Temp\Bentley\MicroStation\10.0.0\AddInLoader1.0)[/quote]
The result of a .NET build is a DLL. The .ma is a temporary file created by MicroStation, not part of your build process.
WPFSample
I built the WPFSample using Viz Studio. I had one problem: Viz Studio complained that the sample .NET framework version 4.0 was earlier than the MicroStation CONNECT U2 DLL framework version 4.5. I modified the project settings for WPFSample in Viz Studio and it built OK in both debug and release.
I confirmed that Viz Studio had placed WPFSample.dll in the mdlapps folder. After I key-in mdl load WPFSample, I have to key-in wpfsample open and wpfsample opendock to see these dialogs...