Laptop to tv through HDMI sound issues

Hello,

On my old laptop I could connect just fine, now the sound will only work through the laptop speakers. I've tried changing the settings, but when I set it to the tv speakers it just shuts off the laptop speakers. I've checked the volume on both tv and laptop to see if it was that, but nothing. My brother suggested something about the HDMI capabilities of the laptop, but I'm not sure if he meant I just can't do it with my HP or if its the HDMI cable that's the problem. Please help?