undefined reference to ur5_demo_descartes::UR5RobotModel::UR5RobotModel()

[TardiSs6]

When trying to build this execise , i get error
"In function boost::detail::sp_if_not_array<ur5_demo_descartes::UR5RobotModel>::type boost::make_shared<ur5_demo_descartes::UR5RobotModel>()' : descartes_node.cpp:(.text._ZN5boost11make_sharedIN19ur5_demo_descartes14UR5RobotModelEJEEENS_6detail15sp_if_not_arrayIT_E4typeEDpOT0_[_ZN5boost11make_sharedIN19ur5_demo_descartes14UR5RobotModelEJEEENS_6detail15sp_if_not_arrayIT_E4typeEDpOT0_]+0x77): undefined reference to ur5_demo_descartes::UR5RobotModel::UR5RobotModel()' "

I am using kinetic