ROS tf tutorial error

$ roslaunch learning_tf start_demo.launch
... logging to /home/username/.ros/log/027e6808-601b-11e7-9409-cc3d82b9eef7/roslaunch-hostname-14033.log
Checking log directory for disk usage. This may take awhile.
Press Ctrl-C to interrupt
Done checking log file disk usage. Usage is <1GB.

started roslaunch server http://hostname:33610/

SUMMARY
========

PARAMETERS
 * /rosdistro: kinetic
 * /rosversion: 1.12.7
 * /turtle1_tf_broadcaster/turtle: turtle1
 * /turtle2_tf_broadcaster/turtle: turtle2

NODES
  /
    broadcaster_fixed (learning_tf/fixed_tf_broadcaster.py)
    sim (turtlesim/turtlesim_node)
    teleop (turtlesim/turtle_teleop_key)
    turtle1_tf_broadcaster (learning_tf/turtle_tf_broadcaster.py)
    turtle2_tf_broadcaster (learning_tf/turtle_tf_broadcaster.py)
    turtle_tf_listener (learning_tf/turtle_tf_listener.py)

auto-starting new master
process[master]: started with pid [14044]
ROS_MASTER_URI=http://localhost:11311

setting /run_id to 027e6808-601b-11e7-9409-cc3d82b9eef7
process[rosout-1]: started with pid [14057]
started core service [/rosout]
process[sim-2]: started with pid [14065]
process[teleop-3]: started with pid [14075]
process[turtle1_tf_broadcaster-4]: started with pid [14076]
Reading from keyboard
---------------------------
Use arrow keys to move the turtle.
process[turtle2_tf_broadcaster-5]: started with pid [14090]
process[turtle_tf_listener-6]: started with pid [14091]
process[broadcaster_fixed-7]: started with pid [14092]
Traceback (most recent call last):
  File "/home/username/catkin_ws/src/learning_tf/nodes/turtle_tf_listener.py", line 32, in <module>
    listener.waitForTransform('/turtle2', '/carrot1', now, rospy.Duration(1.0))
tf.Exception: Lookup would require extrapolation into the past.  Requested time 1499105474.036746979 but the earliest data is at time 1499105479.002878904, when looking up transform from frame [carrot1] to frame [turtle2]. canTransform returned after 1.00482 timeout was 1.
[WARN] [1499105480.196388]: Inbound TCP/IP connection failed: connection from sender terminated before handshake header received. 0 bytes were received. Please check sender for additional details.
[turtle_tf_listener-6] process has died [pid 14091, exit code 1, cmd /home/username/catkin_ws/src/learning_tf/nodes/turtle_tf_listener.py __name:=turtle_tf_listener __log:=/home/username/.ros/log/027e6808-601b-11e7-9409-cc3d82b9eef7/turtle_tf_listener-6.log].
log file: /home/username/.ros/log/027e6808-601b-11e7-9409-cc3d82b9eef7/turtle_tf_listener-6*.log
[broadcaster_fixed-7] killing on exit
[turtle2_tf_broadcaster-5] killing on exit
[turtle1_tf_broadcaster-4] killing on exit
[teleop-3] killing on exit
[sim-2] killing on exit
[rosout-1] killing on exit
[master] killing on exit
shutting down processing monitor...
... shutting down processing monitor complete
done