Philips HTL 3120/12 soundbar connection problem

Hello, after connecting my soundbar to the Philips flat screen TV with an HDMI 1.4 cable to the HDMI/ARC ports as advised in the manual, checked the EasyLink position on auto, no sound comes out of this bar!! the front of the bar confirms the ARC position which flashes, that's all! it only works when turning off the TV speakers and connecting the bar to the TV with a Jack cable!! astonishing, isn’t it, when you’re told that the best sound is obtained with an HDMI cable!! knowing also that the jack cable is reserved for use with headphones! on the forum you read a bit of everything, connect also with an optical or coaxial cable, update software when the user manual doesn’t mention it? where could the problem be to get no sound with such technologies?? thanks in advance if someone can help me, inform me!! regards!