display data in crystal reports

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C#

ASP.NET

Hi All,
This is my code to display data from database using asp.net and c#. But i am unable to display any data in the report.please help me in this:

Here is my Code:

SqlConnection myconn;
SqlCommand cmd;
protected void Page_Load(object sender, EventArgs e)
{
    if (PreviousPage != null)
    {
        DropDownList ddl1 = PreviousPage.FindControl("ddlyear") as DropDownList;
        DropDownList ddl2 = PreviousPage.FindControl("ddlsem") as DropDownList;
        DropDownList ddl3 = PreviousPage.FindControl("ddlsubid") as DropDownList;
        DropDownList ddl4 = PreviousPage.FindControl("ddltype") as DropDownList;
        DropDownList ddl5 = PreviousPage.FindControl("ddlmonth") as DropDownList;
        myconn = new SqlConnection(@"Data Source=TIMSCDR\SQLEXPRESS;Initial Catalog=IAP;Integrated Security=True");
        myconn.Open();
        string str4 = "select stuid,present,absent,working from attendance1 where year = '" + ddl1.Text + "' and sem = '" + ddl2.Text + "' and subid = '" + ddl3.Text + "' and type = '" + ddl4.Text + "' and month = '" + ddl5.Text + "'";
        cmd = new SqlCommand(str4, myconn);
        SqlDataAdapter da4 = new SqlDataAdapter(cmd);
        DataSet ds4 = new DataSet();
        da4.Fill(ds4, "DataTable1");
        ReportDocument report = new ReportDocument();
        report.Load(Server.MapPath("CrystalReport1.rpt"));
        report.SetDataSource(ds4);
        CrystalReportViewer1.ReportSource = report;
        myconn.Close();
    }
}

Thanks in Advance.