Matterslice do not generate support

[zmwd110]

hi , may i ask ,when i use matterslice to slice model,
there is no support part in the final gcode,
for example , i use the configsetting method : set to default,
then i use cmd to run mattersliece,
i use supportTest.stl in SampleSTLs folder
in CMD ,i input : MatterSlice -o 1.gcode supportTest.stl,
but in the final gcode,
there is no support part,
why is that?