Incompatible signal types. The signal type output for the 51-pin VGA is RGB and normally separate H and V sync. The input on the TV YPbPr which is luminance with color difference also known as Component Video. Simply not the same type of signals. If you laptops have Display Port out, you can get for rather low price Display Port > HDMI converters. You should also make sure you name the input PC on the TV in order to make sure it uses PC resolution and color space processing.