Change the TV input to the same number you have plugged in the DVD. So in other words, on the back of the TV, there is a number next to the plug that you used to plug in the DVD. make certain the INPUT of the TV is set to the same number as the number on the plug! That is it.
If it still doesn't work, what make is the TV? Is it Sony also? If it is not, then turn on the DVD player first, then turn on the TV, and verify the Input is set for the proper input!
HDMI IS NOT A STANDARD!
"What does that mean, Mark?"
It means, that not all HDMI devices are REQUIRED to play together. You could have a samsung dvd and a sony TV, and they do not have to play together! That is why we need an HDMI standard that all manufacturers will adhere to. It is the Beta VHS battle all over again, and your pocket book is the victim!