Fabric HAS to be pretreated to retain ink from printers! You need to either buy the pretreated sheets or make your own using Bubble Jet Set. The pretreated fabric is also available in a roll.
There are many sites with info on the net. One I found very helpful was www.breyerpatch.net. Caryl Breyer Fallert has won many awards at major quilt shows and has a lot of free info available.