trouble connecting laptop to HDTV

i currently have a 12in macbook pro and im trying to connect to my new LG led tv. I have a rocketfish HDMI port and HDMI cable connected to the tv but the display wont carry over the tv just says no display connected. the laptop knows its connected because i get the little triangle sqaure docking symbol in the upper left and it detects the LG tv but still will not work anyone have this same issue?