Hello, I bought a Kanex Mini DP to HDMI cable. (not an adapter) So, I want to connect my computer to a Full HD TV. I plugged in the cable. The image is so grainy, literally nothing is visible. What might be the problem? After I plug in the cable, is there something I should do additionally? The image is not mirrored by the way. I see different things on the screens. Plus, I can't control the cursor on the TV.