How to configure /clock topic in launch file - costmap_2d

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Hi,

I have this case, when I use rosrun costmap_2d costmap_2d_node everything works fine and I get my costmap. But I tried to run this node from a launch file, but this warning appears in the log:

[ WARN] [1378418356.560509543]: Costmap2DROS transform timeout. Current time: 1378418356.5604, global_pose stamp: 1.6400, tolerance: 0.3000
[ WARN] [1378418356.622218511]: Could not get robot pose, cancelling reconfiguration

So I supposed was something related with /clock topic. Comparing rosnode info /costmap_2d of both executions, the only difference is this connection when using rosrun:

Connections:
 [...]
 * topic: /clock
    * to: /vinter_sim (<a href="http://gustavo-HPprobook:36184/">http://gustavo-HPprobook:36184/</a>)
    * direction: inbound
    * transport: TCPROS

What should I do to correctly run this node from .launch file?