Have you tried the visualizer in UGS? Does it show anything?
To me the gcode looks wierd, but I have little knowledge of it.
I tried something called DXG Halftone 2.1 and generated some gcode.
There is a thread on the forum where a guy got this working: CNC Halftone images - Using DXF halftone
Vistualizer:
Some lines of the gcode result
G17
G40
G80
G90
G97 S10000
;
M3
;
G0 Z5.00000000
G0 X0.000000000 Y0.000000000
G0 Z10.0000000
;
G0 X3.27534294 Y-418.622742
G0 Z5.00000000
G1 Z-2.24218750 F400
G0 Z5.00000000
G0 X6.81087685 Y-422.158295
G0 Z5.00000000
G1 Z-2.24218750 F400
G0 Z5.00000000
G0 X13.8819447 Y-422.158295
G0 Z5.00000000
G1 Z-2.24218750 F400
G0 Z5.00000000
G0 X10.3464108 Y-418.622742
G0 Z5.00000000
G1 Z-2.24218750 F400
G0 Z5.00000000
G0 X6.81087685 Y-415.087219
G0 Z5.00000000
G1 Z-2.24218750 F400
G0 Z5.00000000
G0 X3.27534294 Y-411.551697