Problem that could not show progress dialog when using SHFileOperation in defined DLL to copy big folder in windows 8

Hello,

     I encounter a problem that, in Windows 8, it will fail to show progress dialog when call SHFileOperation in my DLL(e.g. My.dll) to copy folder. So what is the reason? It works well in Windows 7.

     The detail information is that, I had  one application called A.exe which has main frame(e.g. CMainFrame), it has command to copy folder by calling SHFileOperation, when I directly run this application and click the menu, it will show progress dialog. Now I directly change this application to a DLL called A.DLL, and I creaet another application called B.exe, when B.exe load A.dll, because A.dll has main frame, so we will first call ShowWindow to hide the main window of A.dll, then call interfact function of A.dll to copy big file(using SHFileOperation), in this case, it should show a progress dialog because it take about 10 seconds  to copy folder, but it fail to show the dialog, what is the reason?

     Thanks for any good suggestion.

Following dialog is progress dialog when calling SHFileOperation in Windows 8 system