Error in creating Users

[Rahul]

Hi All,

I am a beginner in refinerycms and to MVC framework, write now I am trying to make a website using refinery.
I installed refinery cms 2.1.5 on ubuntu 14.04, with mentioned version of ruby 2.2 and rails 3.2.15. I am getting below error every time a user is created.

NoMethodError in Refinery::UsersController#create

undefined method `name' for nil:NilClass

I get the same error when admin is created, but I can use it to login and do my work.However, if another user is created with the same error and when it is used to login, then
I can not browse any page and get stuck on same page with just dashboard tab. No logout button is present so I can logout and again login as admin.
Can any one help me out with this?

Regards
Rahul