Duet extruder does not work

Hi,
I am using RepRapPro Duet 0.8.5 on my custom printer. I am using Pronterface. When I want to calibrate extruder by "Extrude" button on interface, It said no tool selected. I send T0 command and M302 P0 commands. Now It says "Extruding 1 mm of filament" but nothing happens.
Moreover, when I set the hotend temperature to 240, nothing happens. "E0 Heat" led does not light.
I think something is wrong in my configurations but I could not find anything.

If you attach your config.g file then we can check it for errors.

By default, cold extrusion is prevented. Send M302 P1 to enable it, not M302 P0.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].