CWWIM4550E An empty or null checkpoint value was passed to an adapter that supports change tracking.
Explanation
If a repository supports change tracking as specified by the 'supportChangeLog' flag for the
repository in the configuration file, then the checkpoint passed for it in the ChangeControl should
not be empty or null.
Programmer response
Try the search again with a valid checkpoint or disable 'supportChangeLog' for that
repository in the configuration file, if the repository adapter is not capable of
change tracking.