I bought an hdmi to mini (micro?) hdmi cord. The cord is from monoprice and it's 10 feet long. When attaching it to my old LG LCD I can get a picture but no sound so I tried it on a bit newer panasonic plasma and I got both sound and picture. What is the reason for this? I've tried rebooting both tv and playbook, plug in and after turning on, trying all the hdmi ports on the tv and turned on/off the hdmi audio option. The tv is a LG 32LB 75.