Action Editor--problem pasting mirrored pose in blender 2.54 beta


I am learning to animate the ManCandy rig and was following the tutorial to create a walk cycle. But am facing problem when copying and pasting the mirrored pose of the first key frame for all to the end keyframe of the walk cycle. It is working fine in blender 2.49. But in 2.54 beta the poses of the bones are just not getting mirrored.

Is it a bug in blender? Is there a walk around this problem.

Thanks in advance.