Civi entity didn't automatically create the table in database

Question

I created a new entity for my extension. These are the steps i followed:

1. Generated the skeletal files using civix generate:entity command
2. Edited the XML schema definitions as i needed.
3. Generate your DAO and SQL files using civix generate:entity-boilerplate command.
4. Generated the database upgrader.

After following these steps i found the 'auto_install.sql' has the sql query to create the table in DB. But when i uninstall the extension and reinstall it again it didn't created the table.

I even executed the sql query manually it works fine but when i reinstall it, it doesn't create the table.. what could be the reason?

Thank you very much in advance!