C# - Print Multiple Report Using GridView - RDLC?

I want to print report based on GridView checkbox. If 3 rows has been choosed, should be 3 reports. My code is like this...

protected void btn_Print_Click(object sender, EventArgs e)
{
if (IsPostBack)
{
try
{
foreach (GridViewRow gvr in grdRV.Rows)
{
RadioButton rbID = (RadioButton)gvr.FindControl("rbID") as RadioButton;
if (rbID != null && rbID.Checked)
{
string sID = grdRV.DataKeys[gvr.RowIndex].Value.ToString().Trim();
if (rbl_Print.SelectedValue == "0")
{
SMTP(sID);
}
else if (rbl_Print.SelectedValue == "1")
{
Material(sID);
}
}
}
}
catch (Exception ex)
{
Session["error"] = ex.Message;
Response.Redirect("MessageBoard.aspx");
}
}
}

private void Material(string sID)
{
string querystring = "../pmis/Reports/RptRFQMatV.aspx?RFQNo=" + lblRFQNo.Text.ToString() + "&ID=" + sID;
Random r = new Random();
string Script = "";
Script += "<script language=JavaScript id='PopupWindow'>";
Script += "confirmWin = window.open(' " + querystring + "','" + r.Next() + "','scrollbars=yes,resizable=1, width=960,height=500,left=50,top=130,status');";
Script += "confirmWin.Setfocus()</script>";
//ClientScript.RegisterStartupScript(typeof(string), "PopupScript", "PopupWindow");
if (!ClientScript.IsClientScriptBlockRegistered("PopupWindow"))
ClientScript.RegisterClientScriptBlock(typeof(string), "PopupWindow", Script);
}

Currently this code can print report the last row only