I am very new to 3D printing (got my Flashforge Creator Pro this week). I have leveled the bed (best to my ability), and did the two nozzle test prints (left and right). I had downloaded a BB-8 snowflake from thingieverse (http://www.thingiverse.com/thing:1034193), opened the file in Simplify3D, created the gcode, saved it to the SD card and tried to print. The bed and extruders heat up but no filament comes out. I went back into the settings in Simplify3D and everything seems to be right but I know I have missed something. If anyone could help me out I'd greatly appreciate it.