Request account module.. Error

Hi all, I am trying to test the request account module developed by @darius . I ended up with this error:

An Internal Error has Occurred org.hibernate.exception.ConstraintViolationException could not insert: [org.openmrs.module.requestaccount.AccountRequest]

If anybody has an idea how to fix this I really appreciate it. Alternatively, I will really appreciate indicating any other method to upload users in bulks.

Thanks again