Web API Authentication Issue

Question

Hello
I created WEB API project in VS and Authentication type I choose is Individual User Account.
After that I created one model class and controller which has [Authorize] parameter on get data method for testing. Everything has default configuration in web.config and etc.

Problem: When I start project and trying to test with Postman basic authentication it returns Unauthorized 401 status, but when I trying to remove [Authorize] attribute it works well. When I use Postman for authorization I choose Basic Auth and in username and password field I use for example user name: user@Karima ben .com and password: 123123. This user and password is registered in local database already.