fail to install rgbdslam on electric
i have used rgbdslamlink text on furete . recently,i install rgbdslamlink text on turtlebot.but failed. when i type :rosmake --rosdep-install rgbdslam the error message is :the svn: OPTIONS the failure https://svn.openslam.org/data/svn/g2o/trunk: server certificate validation failure certificate issuer is not trusted (https://svn.openslam.org). any suggestion is appreciation.