I'm trying to instantiate a Crystal Report class using reflection:

private void _SetupReport()
{
    int ReportId = Convert.ToInt32(Session.Contents["ReportId"].ToString());

    string Command = "SELECT ReportName FROM ApexReports WHERE RecordId = " + ReportId.ToString();
    DataSet dsReportName = DataLayer.ExecuteQuery(Command);

    string ReportClassName = dsReportName.Tables[0].Rows[0]["ReportName"].ToString();

    Report = (ReportDocument)Assembly.GetExecutingAssembly().CreateInstance(ReportClassName);

    CRViewer.ReportSource = Report;
}

Report is null when this runs. The vaariable ReportClassName contains the correct name. What am I doing wrong?