How to solve these error messages from nav2d tutorials.

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Hi everyone.

I try to do the tutorials from nav2D and when I run the tutirialX.launch I get these errors:

[ERROR] [1412367505.742519058, 35.800000000]: Failed to send PAUSE_COMMAND to Navigator.
[ERROR] [1412367510.758595622, 40.800000000]: Failed to send STOP_COMMAND to Navigator.
[ERROR] [1412367517.638542157, 47.700000000]: Failed to send GETMAP_COMMAND to GetMap-Client.
[ERROR] [1412367517.982605682, 48.000000000]: Failed to send EXPLORE_COMMAND to Explore-Client.

I don't know I get these errors, so I would apreciate if someone could help me with this. I wanna post another question from this package: nad2D_localizer need a topic that publishes odometry information or not?

Thank you in advance for any answer.