Hi, caleb.crd is showing errors on the vtkFlRenderWindowInteractor This is the class that allows to manage a VTK window on a FLTK GUI. The CMakeList.txt file in Auxiliary has cmake IF's to only build this directory when FLTK and VTK are available. The symbols: HAS_FLTK and HAS_VTK should exist on the CMakeCache.txt file. Any idea why this is not working ? Thanks Luis