hi i am trying to add data to the database that was created by some one but when am trying to insert or delete or update the exception is raising and entire project is not working properly and the error i am facing is

"A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: SQL Network Interfaces, error: 26 - Error Locating Server/Instance Specified)"

so now what should i do to resolve this error and my connection string is written as

Dim CON As New SqlConnection("Integrated Security=SSPI;
    Persist Security Info=False;Initial Catalog=DIGITALGAMES;
                                       Data Source=TEJUS-PC\SQLEXPRESS")

is there any problem with my connection string ??