Hi, I install gazebo_ros package this morning and when I try to run PR2 simulator I get this error

Warning [parser_urdf.cc:226] multiple inconsistent <gravity> exists due to fixed joint reduction overwriting previous value [true] with [false].
Warning [parser_urdf.cc:226] multiple inconsistent <gravity> exists due to fixed joint reduction overwriting previous value [false] with [true].
Warning [parser.cc:499] XML Attribute[attach_steps] in element[grasp_check] not defined in SDF, ignoring.
Warning [parser.cc:499] XML Attribute[detach_steps] in element[grasp_check] not defined in SDF, ignoring.
Warning [parser.cc:499] XML Attribute[min_contact_count] in element[grasp_check] not defined in SDF, ignoring.
Warning [parser.cc:499] XML Attribute[attach_steps] in element[grasp_check] not defined in SDF, ignoring.
Warning [parser.cc:499] XML Attribute[detach_steps] in element[grasp_check] not defined in SDF, ignoring.
Warning [parser.cc:499] XML Attribute[min_contact_count] in element[grasp_check] not defined in SDF, ignoring.
Warning [parser.cc:314] parse from urdf.
gzserver: /usr/include/boost/variant/detail/visitation_impl.hpp:207: typename Visitor::result_type boost::detail::variant::visitation_impl(int, int, Visitor&, VPCV, mpl_::true_, NBF, W*, S*) [with W = mpl_::int_<20>, S = boost::detail::variant::visitation_impl_step<boost::mpl::l_iter<boost::mpl::l_end>, boost::mpl::l_iter<boost::mpl::l_end> >, Visitor = boost::detail::variant::invoke_visitor<boost::detail::variant::printer<std::basic_ostream<char> > >, VPCV = const void*, NBF = boost::variant<bool, char, std::basic_string<char>, int, unsigned int, double, float, sdf::Vector3, sdf::Vector2i, sdf::Vector2d, sdf::Quaternion, sdf::Pose, sdf::Color, sdf::Time>::has_fallback_type_, typename Visitor::result_type = void, mpl_::true_ = mpl_::bool_<true>]: Assertion `false' failed.

Warning [Visual.cc:748] Unable to get Material[PR2/Black] for Geometry[pr2::base_footprint::base_footprint_visualbase_bellow_link. Object will appear white
Service call failed: transport error completing service call: unable to receive data from sender, check sender's logs for details

Aborted (core dumped)

Gazebo run but the robot only appear halfway

Can someone help me? Thanks