tf2 buffer lookupTransform fails, tf_echo and rostopic echo /tf_static work fine

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I am having difficulties getting a transformation from a robot to the static world frame in a custom node I am writing. I am using Kinetic and I have a robot with a kinect sensor on board providing PointCloud2 data. I am using the robot_state_publisher node to take care of the tf transforms.

Here is a snippet of my launch file that calls the static_transform_publisher and robot_state_publisher:

<!-- send static transform -->
<node pkg="tf2_ros" type="static_transform_publisher" name="vehicle_broadcaster" args="0 0 0 0 0 0 $(arg world_frame) $(arg namespace)$(arg base_link_frame)" />

<!-- start robot state publisher -->
<node pkg="robot_state_publisher" type="robot_state_publisher" name="robot_state_publisher" output="screen" >
  <param name="publish_frequency" type="double" value="50.0" />
  <param name="tf_prefix" type="string" value="$(arg namespace)" />
</node>

NOTE: the $(arg) values are passed in via command line to the launch file. They should be "world", "robot", "/base_link", and "robot", respectively

The reasoning for calling the static_transform_publisher was that I was not getting a base_link -> world transformation. In other words, I couldn't seem to get robot_state_publisher to output a transformation from the robot's frame to an inertial world frame. (I'd be happy to hear suggestions on this, although this is not the main intent of this question).

The node I have is running the following code:

tf2_ros::Buffer tfBuffer;
tf2_ros::TransformListener tfListener(tfBuffer);
geometry_msgs::TransformStamped transformStamped;

try {
    transformStamped = tfBuffer.lookupTransform("world", "robot/kinect_depth_optical_frame", ros::Time(0));
    std::cout << transformStamped << std::endl;
}
catch (tf2::TransformException &ex) {
    ROS_WARN("%s", ex.what());
}

All I am trying to do at this point is find the transformation between the kinect's optical frame and an inertial "world" frame. When I run this node from a launch file, I get the following exception:

[ WARN] [1522870890.897427898, 4.330000000]: "world" passed to lookupTransform argument target_frame does not exist.

This error persists when I use anything as the first argument, with "world" being replaced with whatever is passed in. When I run rosrun tf2_tools view_frames.py, I get a TF tree that looks exactly how I'd expect a working system to look. Unfortunately, since this is my first post, I don't have enough points to upload an image to this question. (Hopefully I can edit it soon to upload the image...)

When I run rosrun tf tf_echo robot/kinect_depth_optical_frame world in a terminal, I get the following output:

At time 0.000
- Translation: [-0.020, -0.060, -0.050]
- Rotation: in Quaternion [0.500, -0.500, 0.500, 0.500]
            in RPY (radian) [1.571, -1.571, 0.000]
            in RPY (degree) [90.000, -90.000, 0.000]

Regardless of whether or not the transformation is actually correct, the fact that I am getting a response means that this transformation is set up and I should be able to look it up using lookupTransform in my node. I also get an output from rostopic echo /tf_static that looks correct as well (I can add that if requested).

I apologize for the long winded explanation, but I am at a loss here ... (more)