Tata Sky HD setup with Sony Home theatre

Hello Gurus,I have recently purchased Tata Sky HD and the tata sky technician set it up with Sony 5.1 Home theatre and LG LCD TV. The HDMI cable from Tata Sky goes to the Lg Tv and the audio cable goes to the Home Theatre. The problem is there is no sound output from the center speaker. I am able to get the sound from the remaining 4 speakers and the woofer.There is no issue with the center speaker because when I play a DVD, I am able to get sound in the center speaker.Can somebody tell me what is the issue and how it can be fixed.