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[WARN] [1426601373.806774699]: Invalid argument passed to canTransform argument source_frame in tf2 frame_ids cannot be empty

The error tells you what the problem is: RViz needs properly initialised Headers to be able to visualise something like a PointCloud2, as it cannot transform the points into their correct location without them.

It would appear that cloud2 does not have its frame_id field set in its header (see the std_msgs/Header documentation). You can probably copy it from the original (input) cloud. If not, set it to another valid frame id and things should start working.