how to getout from the error : The type or namespace name 'CrystalReport1' could not be found

protected void bt_rep0_Click(object sender, EventArgs e)
    {
        string sql;
        sql = "SELECT m.[proj_ID] ,pt.[proj_type_ff],m.[proj_no],m.[proj_prop_no],m.[Proj_title],pr.[investigator_name], pa.[investigator_name],fa.[fund_agency_acronym],m.[Budg],m.[from_date],m.[close_date],pe.[ext_date],m.[RptNo],m.[status] FROM [monitor].[dbo] .[MENU] m LEFT OUTER JOIN [monitor].[dbo].[pro_investigator] pr ON m.[investgator_id] = pr.[investgator_id] LEFT OUTER JOIN [monitor].[dbo] .[project_type] pt ON m.[proj_type_id]  = pt.[proj_type_id] LEFT OUTER JOIN [monitor] .[dbo] .[project_AItable] pa on m.[proj_ID] = pa.[proj_ID] LEFT OUTER JOIN [monitor].[dbo].[project_FAtable] pf on m.[proj_ID] = pf.[proj_ID] LEFT OUTER JOIN [monitor] .[dbo] .[fund_agency] fa on pf.[fund_agency_id] = fa.[fund_agency_id] LEFT OUTER JOIN [monitor] .[dbo] .[project_ext] pe on m.[proj_ID] = pe.[proj_ID] order by m.[proj_ID] ";

        c27.cmd = new System.Data.SqlClient.SqlCommand(sql, c27.connect());
        c27.da = new System.Data.SqlClient.SqlDataAdapter(sql, c27.connect());
        c27.da.Fill(c27.ds);
        c27.da.Fill(c27.ds, "ss");
        //MessageBox.Show(c27.ds.Tables[1].Rows.Count.ToString());


       //crystalr
        CrystalReport1 objRpt = new CrystalReport1();//error generating code
        objRpt.SetDataSource(c27.ds.Tables[1]);
        CrystalReportViewer1.ReportSource = objRpt;

        ////////////CrystalReportViewer1;
        ////////////crystalReportViewer1.Refresh();
    }

Error 48 The type or namespace name 'CrystalReport1' could not be found (are you missing a using directive or an assembly reference?)