Your DXF file have one polyline and une view (VPORT)
Opening it with LibreCAD the polyline are read and the current view are set using vport data.
But your polyline are on right of current view, simply exec "view->auto zoom" to show all the drawing
thank you for your reply. I tried it without success. LibreCAD finds and shows alls Layers, but not the polyline. I zoomed out and out and out... but I could not see anything. I tried to select the polyline via a rectangle containing the complete view. But LibreCAD selected no elements...