issue with ApproximateTime

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I am using a system that requires and rgb image, depth image, and camera info . Its does this by using the following:

 typedef ApproximateTime<sensor_msgs::Image, sensor_msgs::Image, sensor_msgs::CameraInfo> SyncPolicy;

My problem is that the bag file I am using does not publish camera info messages. So I tried to publish it independently. But but system never invokes , I set the header to rospy.Time.now() which set the vars to zero. How I can I get the system to invoke the callback in a situation like this.

The system I am using is: depth_image_proc/point_cloud_xyzrgb The node does allow for :

but seem to have not effect: there is a possibility that there is an issue with the time stamps in the bag file. But I have not looked at that yet.