After few tutorials a did the basic webcamera streaming program using EMGUCV 2.2.1. Then I decided to upgrade EMGUCV version on 2.4.2 and the same program threw me an exception 'Emgu.CV.CvInvoke'. So I was searching an Internet for solution, tried a lot of them and none of them worked for me. I'm using VS 2012 x64(a lot of solutions are for VS 2010) and 64bit WIN7. After several weeks of fighting with the problem, I decided to downgrade on 2.3 and suddenly it worked again. So I'm posting this question to ask: "Does anyone know what/where the problem is?" and to help people with same problem.