Did you 'type' the expression? Always select the grid from the list of layers and variables, then select the operands and numbers like on a calculator. In that way, the expression will be correct.
Try
Con((bells >= 3150) & ( bells < 3400), 1, 0)
no typing... except for the grid name... and try a *.tif in a folder rather than a geodatabase (ie c:\GISwork\...\rast6.tif