public class SSRSReportsGenerator: MarshalByRefObject, ISSRSReports
{
    // Creating Reporting Service Object.
    ReportingService2005 RS;
    public SSRSReportsGenerator()
    {
        RS = new ReportingService2005();
        RS.Credentials = System.Net.CredentialCache.DefaultCredentials;
    }
    public void CreateDataSource()
    {
        string name = "DataSource1";
        string parent = "/MTVN Reports";

        // Define the data source definition.
        DataSourceDefinition definition = new DataSourceDefinition();
        RS.Credentials = System.Net.CredentialCache.DefaultCredentials;
        RS.UseDefaultCredentials= false;

        definition.CredentialRetrieval = CredentialRetrievalEnum.Integrated;
        definition.UserName = "sa";
        definition.Password = "sa123";
        definition.ConnectString = "";
        definition.Enabled = true;
        definition.EnabledSpecified = true;
        definition.Extension = "DATASET";
        definition.ImpersonateUser = false;
        definition.ImpersonateUserSpecified = false;
        definition.Prompt = null;
        definition.WindowsCredentials = false;

        try
        {
            RS.CreateDataSource(name, parent, true, definition, null); // Getting error on this line
        }
        catch (Exception e)
        {
            Console.WriteLine(e.Message);
        }
    }
}