HD Channels in Columbia

I recently purchased a Sony KD-34XBR960 and it looks great. I'm trying my luck at receiving the local HD signals in the Columbia area with my built in tuner. I can receive the HD broadcasts from WLTX 19.1 and WOLO 25.1 great, but can't get the WIS 10.1 or Fox station 57.1 signals. I live near the Veterans Hospital on US378 in Columbia. I don't have a antenna hook up, but the two channels I do receive come in perfect without it. Any suggestions as why all the HD broadcast are not being receives. If I can't get all the broadcast signal with my tuner I guess I'll go ahead and get the digital cable from Time Warner. Any suggestions will be greatly appreciated.


Thanks,


SundanceKid