Unable to retrieve the children from current page

hi, I am using umbraco 7, There will be two pages I created one is home and another is login. I added the login as child under the home page.

When comes to dot net I created one controller and in that I am retrieving the login by using like this Page=CurrentPage.Children.FirstOrDefault(c => c.DocumentTypeAlias == "login"); I am getting Null value reference

Please anyone help me to solve this problem

Thanks,