Connect my tv to my computer

Hello,
i try to connect my computer to my tv with a vga cable i can not . when i go to set up multiple displays in nvidia control panel it only show only one display , when i click select the display you would like to use i see my monitor and the second one said my displays is not shown in the list if i click rigorous display detection it can not fund my second monitor , my computer i had before i was connected with same vga cable it was working .
thnak you for your help
alain