Asp.net Mvc Scaffolding

Question

Hi,
     I am new to Asp.net Mvc .I have created simple scaffolding app which perform crud operation.
What is happening it is adding only one record in it, and update and delete also to single record. I am not able to add new record. 

 Error which it is showing is 
An exception of type 'System.Data.Entity.Infrastructure.DbUpdateException' occurred in EntityFramework.dll but was not handled in user code:


Code FLow : 
1) Created one Test data base SQL 4 colums, ID as int, and 3 columns with nvarchar(50).
2)Added ADO.net Entity to Model.
3)And One controller for Insert update delete.

Its Adding , updating, deleting just one record, Not able to add other record.


Plz help

Thnx in advance