I can't get my preview screen to show on my TV monitor

[Newbie Filmmaker 1]

I have a regular computer monitor that I am using for my editing timeline/software (Sony Vegas Pro). And I would like to use a TV as monitor to show me just the preview screen as I edit.

I've hooked up the TV to my computer with an HDMI cord. Now, on the TV screen, I can see my computer desktop (sort of -- it's like the far right side of the desktop). So we know the computer is showing on the TV.

But I can't figure out how to get the editing preview screen to show on the TV when I am editing. I clicked Options/Preferences/Preview Device, and I'm not seeing my TV set listed there. Very confused. There's also a button called "Video Preview on External Monitor." When I click that, it simply gives me the preview screen as "full screen" on my computer monitor (but no effect on the TV monitor.)

If anyone has any ideas / suggestions.. it would be greatly appreciated. Horrifically frustrating. THANK YOU!!
(oh, the computer is a Lenovo K450e)

 

[Alcove Audio]

I haven't worked with Vegas in years, and haven't worked on a PC in I can't even remember how long....

However...

I use a Canopus/Grass Valley ADVC110 video interface with my Mac running Pro Tools and Digital Performer for getting the picture onto a TV screen. (I replaced my ADVC100 a while back after 10+ years of very solid service.)

http://www.bhphotovideo.com/c/produ...9_ADVC_110_Bidirectional_Media_Converter.html

Firewire output from my Mac to the ADVC110, I use the S-Video out to my TV. Works first time, every time right out of the box or when a new computer is hooked up - as long as I don't make any errors.

 

[Sweetie]

I have no idea about Vegas Pro.

How have you set up these devices to be monitors in your operating system? It sounds like you're running multiple devices at the same time. Are you using the multiple display mode you want to use?

What resolution is the TV? Has it been set correctly on your computer?

Does it work properly outside Vegas?

The rest is difficult to understand what you're doing.