Need help making laptop-to-TV work (via HDMI)

Hi guys... registered a while ago but this is my first post. Here's my issue.

I've hooked up my laptop to my TV via HDMI cable, trying to make the TV act as a monitor. Haven't been able to make it work yet. Details...

-- Laptop is a Dell Inspiron, model N5010 running Windows 7. Video driver appears to be Intel.
-- TV is a Toshiba HDTV.
-- The two are connected directly via HDMI cable (no converters or anything). I've confirmed the TV is on the correct input, but it shows "No video signal."
--On the laptop, when I try to set up a new monitor at Control Panel > Appearance and Personalization > Display > Screen Resolution, it only shows the laptop monitor. When I click on "Detect," I get a gray-colored square to the right of the main monitor that says "Another Display Not Detected."
-- I checked to see if the laptop could detect the connected TV. I went to Control Panel > Hardware and Sound > Devices and Printers, and it's not there (nor is anything that resembles a monitor). When I click "Add a device," the only thing the laptop detects is my printer, which is actually already connected.

-- Interesting note: When I turn the TV off/on again, once it fires up, my laptop screen goes black for a second and it makes an audible tone. That leads me to believe 1) the cable is functioning & hooked up correctly and 2) the laptop knows *something* is connected and is reacting to it, but I can't seem to figure out how to make it work.

Thanks so much for any help!