Some major role vga extension cable for

VGA extension cable is a few empty legs . 5 m of the line is entirely possible . If your graphics card is DVI interface before , then you need to set up a second monitor and the first monitor the same. Some  WISDOM mini usb connector vga extension cable dual interface display there is a button to select the input interface can be extended is possible bq, but there may be too long too 8406quy 9186 that resulted in a low signal attenuation to below the detection threshold of a TV cable TV to get in front of the notebook , bought the line alone try, to determine which lines are easy to use , if no problem , then it should be too much to extend the signal attenuation is possible, but WISDOM pcb spring terminal block  there are may be too long , resulting in signal attenuation too , vga extension cable to the TV so low below the threshold of detection . That is a problem with your line quality connection is not wrong but the extension cord should be increased with the length of male and female that point does not cause signal interruption of this phenomenon is normal, because VGA is an analog signal transmission , the longer the line the usb 2.0 cable  more  attenuation powerful.
At the same time the quality of the line attenuation great impact , it is recommended to buy a good brand is the best VGA extension cable