The tv transmissions in green are very strong , and the radio shack indoor antenna is nonamplified so thats correct. Might be something wrong with the connector or antenna wire that connects to the tv. Try one of these nonamplified antennas.
http://forum.tvfool.com/showthread.php?t=233 , And read and understand this about Real digital tv channels and Virtual digital tv channels.
http://forum.tvfool.com/showthread.php?t=695