Aravind,
Did you update the datasource file so you have changes to publish?
The steps are either
1. make changes to your class persistence
2. press the “Update Data Source…” tool at the top of the Attribute Mappings tab in the Class Persistence Mapping
3. review and accept your changes
(now you datasource will have changes)
4. Right click your datasource and choose “Generate Upgrade Steps…”
5. Review and accept the changes after bumping the version number
6. Set the version number of your model to the new version number using the Model Library
OR
1. make manual changes to your datasource
2. continue from step 4 above