I have no idea. AVerMedia used to have a forum, but they have gotten rid of that for some reason. There doesn't seem to be a way to contact them.
So you are streaming in 720p 50 FPS. I would instead go with 720p 30 FPS at 2000 kbps. This is what a lot of people consider to be an okay starting point. If you want better image quality I would suggest going lower than 720p, but keeping the FPS at 30.
Have you set up the Stream Engine settings correctly? Make sure the FPS settings are correct. I've found that via Stream Engine the only FPS that works consistently is 30 FPS. Higher FPS tends to induce laggy video for me.
Start with adjusting your video settings, though. 720p 50 FPS with a Medium CPU preset is fairly high. Besides, 3000 kbps is way too little bits for that anyway, and it will cause most viewers to buffer.