CORN has had a rough start to 2012. Over the past few weeks, the fund has given back nearly all of the gains seen during its late-December run up. The futures-tracking iPath Dow Jones UBS Natural Gas Subindex Total Return ETN ( GAZ) is struggling as well. With over 1% losses, GAZ has extended its losing streak to seven sessions. All prices as of 2:14 PM EST Written by Don Dion in Williamstown, Mass.