c# - cannot send email through button asp.net -

im planning send email image attached receiver. when click on button, nothing happens. error or success note not visible. can me out on this? thank you. here codes: aspx

<%@ page title="" language="c#" masterpagefile="~/admin/site1.master"   autoeventwireup="true" codebehind="submitpurchaseorder.aspx.cs" inherits="islandgas.admin.submitpurchaseorder" %> <asp:content id="content1" contentplaceholderid="title" runat="server"> </asp:content> <asp:content id="content2" contentplaceholderid="content" runat="server"> <form id="form1" runat="server"> <div> <table style=" border:1px solid" align="center"> <tr> <td colspan="2" align="center"> <b>purchase order supplier</b> </td> </tr> <tr> <td> gmail username: </td> <td> <asp:textbox id="txtusername" runat="server"></asp:textbox>                                             <asp:requiredfieldvalidator id="requiredfieldvalidator1" runat="server"                                          errormessage="user name required." display="dynamic" controltovalidate="txtusername"                                          forecolor="red"></asp:requiredfieldvalidator>                                         <asp:regularexpressionvalidator id="regularexpressionvalidator7" runat="server"                                          errormessage="invalid format." display="dynamic"                                          validationexpression="\w+([-+.']\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*"                                          controltovalidate="txtusername" forecolor="red"></asp:regularexpressionvalidator> </td> </tr> <tr> <td> gmail password: </td> <td> <asp:textbox id="txtpwd" runat="server" textmode="password"></asp:textbox> <asp:regularexpressionvalidator id="regularexpressionvalidator1" runat="server"                                              errormessage="no special characters." controltovalidate="txtpwd" forecolor="red"                                              validationexpression="^[a-za-z0-9]+$" display="dynamic"></asp:regularexpressionvalidator>                                         <asp:requiredfieldvalidator id="requiredfieldvalidator2" runat="server"                                          errormessage="password required." display="dynamic" controltovalidate="txtpwd"                                          forecolor="red"></asp:requiredfieldvalidator> </td> </tr> <tr> <td> subject: </td> <td> <asp:textbox id="txtsubject" runat="server"></asp:textbox> <asp:regularexpressionvalidator id="regularexpressionvalidator3" runat="server"                                              errormessage="no special characters." controltovalidate="txtsubject" forecolor="red"                                              validationexpression="^[a-za-z0-9 ]+$" display="dynamic"></asp:regularexpressionvalidator>                                         <asp:requiredfieldvalidator id="requiredfieldvalidator3" runat="server"                                          errormessage="subject required." display="dynamic" controltovalidate="txtsubject"                                          forecolor="red"></asp:requiredfieldvalidator> </td> </tr> <tr> <td> to: </td> <td> <asp:textbox id="txtto" runat="server"></asp:textbox> <asp:regularexpressionvalidator id="regularexpressionvalidator2" runat="server"                                          errormessage="invalid format." display="dynamic"                                          validationexpression="\w+([-+.']\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*"                                          controltovalidate="txtto" forecolor="red"></asp:regularexpressionvalidator>                                         <asp:requiredfieldvalidator id="requiredfieldvalidator4" runat="server"                                          errormessage="recipient required." display="dynamic" controltovalidate="txtto"                                          forecolor="red"></asp:requiredfieldvalidator> </td> </tr> <tr> <td> attach file: </td> <td> <asp:fileupload id="fileupload1" runat="server" /> <asp:requiredfieldvalidator                 id="requiredfieldvalidator5" runat="server"                  errormessage="please upload image" controltovalidate="fileupload1"                  forecolor="red"></asp:requiredfieldvalidator>                 <asp:regularexpressionvalidator id="regularexpressionvalidator5" runat="server"                      errormessage="invalid file type"                      controltovalidate="fileupload1" forecolor="red"                      validationexpression="^.*\.(jpg|jpg|gif|gif|doc|doc|pdf|pdf|png|png)$"></asp:regularexpressionvalidator> </td> </tr> <tr> <td valign="top"> body: </td> <td> <asp:textbox id="txtbody" runat="server" textmode="multiline" columns="30" rows="10" ></asp:textbox> <asp:regularexpressionvalidator id="regularexpressionvalidator6" runat="server"                                              errormessage="no special characters." controltovalidate="txtbody" forecolor="red"                                              validationexpression="^[a-za-z0-9]+$" display="dynamic"></asp:regularexpressionvalidator>                                         <asp:requiredfieldvalidator id="requiredfieldvalidator6" runat="server"                                          errormessage="message body required." display="dynamic" controltovalidate="txtbody"                                          forecolor="red"></asp:requiredfieldvalidator> </td> </tr> <tr> <td> </td> <td> <asp:button id="btnsubmit" text="send" runat="server" onclick="btnsubmit_click" /> </td> </tr> </table> </div> </form> </asp:content> 

and code behind:

protected void btnsubmit_click(object sender, eventargs e)     {         try         {             mailmessage msg = new mailmessage();             // sender e-mail address.             msg.from = new mailaddress(txtusername.text);             // recipient e-mail address.             msg.to.add(txtto.text);             msg.subject = txtsubject.text;             // file upload path             string filename = fileupload1.postedfile.filename;             string mailbody = txtbody.text + "<br/><img          src=cid:companylogo>";             string filename = path.getfilename(filename);             msg.attachments.add(new attachment(fileupload1.postedfile.inputstream, filename));             //linkedresource myimage = new linkedresource(filename);             // create html view             alternateview htmlmail = alternateview.createalternateviewfromstring(mailbody, null, "text/html");             // set contentid property. value of contentid property must same             // src attribute of image tag in email body.              //myimage.contentid = "companylogo";             // htmlmail.linkedresources.add(myimage);             msg.alternateviews.add(htmlmail);             // remote smtp server ip.             smtpclient smtp = new smtpclient();             smtp.host = "smtp.gmail.com";             smtp.port = 587;             smtp.credentials = new system.net.networkcredential(txtusername.text, txtpwd.text);             smtp.enablessl = true;             smtp.send(msg);              msg = null;             //clientscript.registerstartupscript( "<script>alert('mail sent thank you...');if(alert){ window.location='sendmail.aspx';}</script>");             response.write("<script>alert('email sent');</script>");          }         catch (exception ex)         {             response.write("<script>alert('unable send email');</script>");             console.writeline("{0} exception caught.", ex);         } 

is main div wrapped in form?

<form runat="server" id="frm1"> .... </form>