SQL Server database not undating

Dear Friends,

I am using Visual Studio 2005 with SQL Server Menegment Studio 2005.

On the web form i have DetailsView

I alrady make true for AutoGenerateEdit, Delete and Insert button

My DetailsView looks perfect and when i View in Browser it fatch and display data perfectly but when i try to update or insert data recored it show me following error.

Exception Details: System.NotSupportedException: Updating is not supported by data source 'SqlDataSource1' unless UpdateCommand is specified.

Kindly help be what to do?