我尝试打印销售发票时出现问题

private void button1_Click(object sender, EventArgs e)
{
    hesham2020Entities2 db = new hesham2020Entities2();
    string u;
    u = textBox1.Text.Trim();
    var y = from v in db.inv_detail
            from s in db.invoice_head 
            where s.invno==u
            select new
                {v.unit,v.qty,v.p_no,v.description,v.price,v.tot_price,s.invno,s.customer_id,s.inv_dat,s.po_no,s.total,s.currency};
    CrystalReport6 crt = new CrystalReport6();
    crt.SetDataSource(y);
    crv9.Refresh();
    crt.SetParameterValue(0, comboBox2.SelectedItem);
    crt.SetParameterValue(1, comboBox3.SelectedItem);
    //crt.SetParameterValue(2, textBox1.Text);
    crv9.ReportSource = crt;
    crv9.Refresh();
}

当我尝试打印此发票时，如果发票明细包含3行，则它打印9行，这意味着每行打印3次，但是当发票明细包含1行时，则打印1行。我不知道错误的原因