System.Data.SqlClient.SqlError: The backup set holds a backup of a database other than the existing CascadingDDL database

Hi there

I have backup file and I want Restore it into my sqlserver but when I did it this error happen

------------------------------ ADDITIONAL INFORMATION: System.Data.SqlClient.SqlError: The backup set holds a backup of a database other than the existing 'CascadingDDL' database. (Microsoft.SqlServer.Smo) For help, click: http://go.microsoft.com/fwlink?ProdName=Microsoft+SQL+Server&ProdVer=10.50.1447.4+((KJ_RTM).100213-0103+)&LinkId=20476 ------------------------------ BUTTONS: OK ------------------------------

What should I do?

Best regards