external display works well on screen, but impossible to get a video

Hello all, I have a worry ... I have a laptop with external display works well on screen, but impossible to get a video.

I tried with another laptop, the video works well.

I will try to update the video drivers, another idea?

Thank you all!

The video projector does not support the screen resolution?
Or simply the video projector does not work?
The output selected is not good? Or was not self-detected?
The cable is no longer good?

I indicated that I did the test with another laptop , so the video market, the output is good, was detected, and cable is good.

I will try with another resolution, the laptop is 1280 * 800, the external display works well with a 17-inch LCD screen.

puts the laptop in 800x600 or 640x480 ...

With my laptop in 17 ", when I plug in the cable videopro, it detects new hardware, namely, a screen plug and play, but pressing Fn + F4 just say that there no external display

What makes them work on other portable and not these two? Cable videopro too long?