Offset using Xylinus

Hello everyone,

I am discovering, Rhino, Grasshoper and Xylinus.

When I slice, I receive a G-code but the first layer starts at the second layer...

For example, I give a 0.2mm layer height but the gcode starts at 0.4 (or more likelly twice the layer height)...

I thought it came from the geometrie but I checked. Then I thought about using a .stl rather than a geometry I did in Rhino but that wasn't the problem.

I am now thinking about copy and paste the first layer but at the right height or offsetting all the Z coordinates.

If anyone have an idea or know what is wrong (it may be obvious but I am a beginner) I will really enjoy it.

Thank ;-)