Hello! I've been trying to configure communication between laptop and youbot Kuka using wireless network. ROS installed on the laptop is Kinetic and ROS installed on the mobile robot is Hydro. In my opinion i configured correctly .bashrc files on the two machines. The laptop is master. When i start

roscore

and

 rosrun turtlesim turtelesim_node

on the master machine everything is fine. However..when i write

rostopic list

on the slave machine (kuka Youbot) there is a mistake and i don't know how to solve the problem. I will be very grateful to help. The error is:

youbot@ubuntu:~$ rostopic list
Traceback (most recent call last):
  File "/opt/ros/hydro/bin/rostopic", line 35, in <module>
    rostopic.rostopicmain()
  File "/opt/ros/hydro/lib/python2.7/dist-packages/rostopic/__init__.py", line 1673, in rostopicmain
    _rostopic_cmd_list(argv)
  File "/opt/ros/hydro/lib/python2.7/dist-packages/rostopic/__init__.py", line 1614, in _rostopic_cmd_list
    exitval = _rostopic_list(topic, verbose=options.verbose, subscribers_only=options.subscribers, publishers_only=options.publishers, group_by_host=options.hostname) or 0
  File "/opt/ros/hydro/lib/python2.7/dist-packages/rostopic/__init__.py", line 860, in _rostopic_list
    master = rosgraph.Master('/rostopic')
  File "/opt/ros/hydro/lib/python2.7/dist-packages/rosgraph/masterapi.py", line 100, in __init__
    self._reinit(master_uri)
  File "/opt/ros/hydro/lib/python2.7/dist-packages/rosgraph/masterapi.py", line 118, in _reinit
    raise ValueError("invalid master URI: %s"%(master_uri))
ValueError: invalid master URI: 192.168.1.248:11311

export ROS_MASTER_URI=master_hostname:11311

export ROS_MASTER_URI=http://master_hostname:11311