Sorry :(, I forgot an essential point. All the function (from App to the Dll ) was at other Thread ("Dll thread"). Not in the main (GUI) thread, but in the same one (using queue) The init(…) and other function first enter to Q and the pulled by the "Dll Thread") koby

I have just started trying my hand at DirectX. Have you installed the SDK Update from... http://www.microsoft.com/downloads/details.aspx?FamilyId=9216652F-51E0-402E-B7B5-FEB68D00F298&displaylang=en