Problem vith VPI Scout and Dynavector 20XH

I have a VPI Scout with Dynavector 20XH cartridge, and after setting up the tone arm and cartridge according to the Scout manual, I noticed that sound was coming from only one channel. I looked closely and could not find any bad connections. When I touched the white cable at the cartridge I could hear a loud hum coming from one speaker. I checked the ground and they were well tightened, but I still head the loud hum when I touch the white cable. When I rub my finger on the needle of the cartridge, I did not get the usual loud sound from the speaker, I had to turn the volume up high before I could hear anything like buzzing sound when I touch the needle. The turntable was working fine before, all I did was to set it up again and adjusted the height of the tone arm per the manual, then this problem stared. Any ideas?