question about exporting and importing via JCR api

[Betty Chang]

Hi --

Am I supposed to be able to export and import my complete repository using JCR 
calls?
I used Session.exportSystemView() to save everything to a file,
but when I use Workspace.importXML(),  I get a ConstraintViolationException 
about
  "/jcr:root/jcr:system: mandatory child node (http://www.jcp.org/jcr/1.0) 
versionStorage does not exist"

Thanks

Betty