Trying for the first time. Geting this error messsage in ruby console on export. Sketchup 2014 Mac:

Error: #<NoMethodError: undefined method alpha' for nil:NilClass> /Users/m_singer/Library/Application Support/SketchUp 2014/SketchUp/Plugins/t2h_su2objmtl_mitsuba/mod_mitsuba_material.rb:1145:in matcoder'
/Users/m_singer/Library/Application Support/SketchUp 2014/SketchUp/Plugins/t2h_su2objmtl_mitsuba/mod_mitsuba_material.rb:1093:in block in export_this_material' /Users/m_singer/Library/Application Support/SketchUp 2014/SketchUp/Plugins/t2h_su2objmtl_mitsuba/mod_mitsuba_material.rb:1083:in each'
/Users/m_singer/Library/Application Support/SketchUp 2014/SketchUp/Plugins/t2h_su2objmtl_mitsuba/mod_mitsuba_material.rb:1083:in export_this_material' /Users/m_singer/Library/Application Support/SketchUp 2014/SketchUp/Plugins/t2h_su2objmtl_mitsuba/mod_mitsuba_material.rb:804:in export_mtl_material'
/Users/m_singer/Library/Application Support/SketchUp 2014/SketchUp/Plugins/t2h_su2objmtl_mitsuba/mitsuba_main.rb:311:in export_geom_xml' /Users/m_singer/Library/Application Support/SketchUp 2014/SketchUp/Plugins/t2h_su2objmtl_mitsuba/mitsuba_main.rb:125:in export'
/Users/m_singer/Library/Application Support/SketchUp 2014/SketchUp/Plugins/t2h_su2objmtl_mitsuba/mitsuba_main.rb:23:in startexport' /Users/m_singer/Library/Application Support/SketchUp 2014/SketchUp/Plugins/t2h_su2objmtl_mitsuba/mod_mitsuba_settings.rb:109:in block in render_show_webdialog'
-e:1:in `call'