roswtf- error * service [/gazebo/set_logger_level] appears to be malfunctioning:

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roswtf command gave following errors:

dteja@teja:~$ roswtf
WARNING: Package "ompl" does not follow the version conventions. It should not contain leading zeros (unless the number is 0).
Loaded plugin tf.tfwtf
No package or stack in context
================================================================================
Static checks summary:

No errors or warnings
================================================================================
Beginning tests of your ROS graph. These may take awhile...
analyzing graph...
... done analyzing graph
running graph rules...
ERROR: connection refused to [http://teja:41041/]
... done running graph rules

Online checks summary:

Found 2 warning(s).
Warnings are things that may be just fine, but are sometimes at fault

WARNING The following node subscriptions are unconnected:
 * /gazebo:
   * /clock

WARNING The following nodes are unexpectedly connected:
 * unknown (http://teja:37571/)->/rosout (/rosout)


Found 3 error(s).

ERROR /use_simtime is set but no publisher of /clock is present
ERROR Could not contact the following nodes:
 * /gazebo

ERROR Errors connecting to the following services:
 * service [/gazebo/set_logger_level] appears to be malfunctioning: Unable to communicate with service [/gazebo/set_logger_level], address [rosrpc://teja:51809]
 * service [/gazebo/get_loggers] appears to be malfunctioning: Unable to communicate with service [/gazebo/get_loggers], address [rosrpc://teja:51809]

Can someone say how to solve this issue? Thanks in advance.