Dell CRT Monitor

Last week, I tried to connect the Dell CRT Monitor & the visualizer via the Video Splitter in the classroom, but it can't display the things on the visualizer.

Today, I try to replace VGA wires, the visualizer & the Video Splitter but it can't display the things on the visualizer. Then, replace it & I use others brand's CRT Monitor, these CRT Monitor can display the things on the visualizer.

I hate DELL~!