no display with triangle list a<1.0

edit

I cannot get to display the triangle_list with an alpha less than 1.0. Is this a known bug?

For reference below is my code. Basically I am trying to display a laser fan

 visualization_msgs::Marker scan_marker;
 scan_marker.header.frame_id = "/robot_0/base_laser_link";
 scan_marker.header.stamp = ros::Time::now();
 scan_marker.ns = "scan";
 scan_marker.type = visualization_msgs::Marker::TRIANGLE_LIST;
 scan_marker.action = visualization_msgs::Marker::ADD;
 scan_marker.id = 0;
 scan_marker.scale.x = scan_marker.scale.y = scan_marker.scale.z = 1.0;
 std_msgs::ColorRGBA scan_color;
 scan_marker.pose.position.x = 0.0;
 scan_marker.pose.position.y = 0.0;
 scan_marker.pose.position.z = 0.0;
 scan_marker.pose.orientation.x = 0.0;
 scan_marker.pose.orientation.y = 0.0;
 scan_marker.pose.orientation.z = 0.0;
 scan_marker.pose.orientation.w = 1.0;
 scan_color.a = 0.8f;
 scan_color.r = 0.25f;
 scan_color.g = 0.5f;
 scan_color.b = 0.9f;
 geometry_msgs::Point temp;

 for (int i = 0; i < cloud.points.size() - 1; i++) {
   for (int j = -1; j < 2; j++) {
     temp.x = j == -1 ? 0 : cloud.points[i + j].x;
     temp.y = j == -1 ? 0 : cloud.points[i + j].y;
     temp.z = j == -1 ? 0 : cloud.points[i + j].z;
     scan_marker.points.push_back(temp);
     scan_marker.colors.push_back(scan_color);
  }
}

Following is the image for alpha=1.0. There is nothing visible for alpha = 0.8 https://dl.dropboxusercontent.com/u/8...