000781 : Can not reuse the schema of versioned data. Please unregister the data as versioned before reusing the schema.
Description
The ReUse schema option is available for checkout/check-in replication and requires the data on the checkout geodatabase to be unversioned.
Solution
Unversion the data and try the checkout again. See the Unregister As Versioned tool help for more information.
11/18/2010