c# - ASP.Net Button not raising postback -

i've simple page in 1 of our web applications, has following markup:

    <%@ page language="c#" autoeventwireup="true" codebehind="newupload.aspx.cs" inherits="mass_upload.newupload" masterpagefile="~/master" title="document mass upload" %> <asp:content id="content1" contentplaceholderid="head" runat="server">     <link rel="stylesheet" type="text/css" href="./../css/scrollingtable.css" />     <script type="text/javascript" src="../help/helppopup.js" /> </asp:content> <asp:content id="content2" contentplaceholderid="centerh1" runat="server">     document mass upload <a href="javascript:loadhelpvid(5)"><img style="border:none;" src="../help/help_icon.gif" /></a> </asp:content> <asp:content id="content3" contentplaceholderid="centerbody" runat="server">     <h3>add new upload</h3>     <table class="list">         <tr>             <td class="label" style="text-align:right;">local file:</td>             <td class="normal">                 <asp:fileupload id="fufilename" runat="server" width="405" />                 <asp:requiredfieldvalidator id="requiredfieldvalidator1" text="*"                             errormessage="a file upload required"                             display="dynamic"                             controltovalidate="fufilename"                             validationgroup="documentupload"                             runat="server" />             </td>         </tr>         <tr>             <td class="label" style="text-align:right;">document description:</td>             <td class="normal">                 <asp:textbox id="txtdescription" runat="server" width="405" maxlength="50" />                 <asp:requiredfieldvalidator id="requiredfieldvalidator3" text="*"                             errormessage="document description required field"                             display="dynamic"                             controltovalidate="txtdescription"                             validationgroup="documentupload"                             runat="server" />             </td>         </tr>         <tr>             <td class="label" style="text-align:right;">document type:</td>             <td class="normal">                 <asp:dropdownlist id="dddoctype" runat="server" width="405"/>                 <asp:requiredfieldvalidator id="requiredfieldvalidator2" text="*"                             errormessage="document type required field"                             display="dynamic"                             controltovalidate="dddoctype"                             validationgroup="documentupload"                             runat="server" />             </td>         </tr>         <tr>             <td class="label" style="vertical-align:top;text-align:right;">customer types:</td>             <td class="normal">                 <asp:label id="lblsinglecustomer" text="specific code:" runat="server" /><asp:textbox id="txtsinglecustomer" runat="server" width="100px" /><br />                 <asp:checkboxlist id="cblcustomertypes" runat="server" width="405px" repeatdirection="horizontal" repeatcolumns="5" repeatlayout="table" cellpadding="10" cellspacing="0" />             </td>         </tr>         <tr>             <td class="normal" colspan="2">&nbsp;</td>         </tr>         <tr>             <td class="normal" colspan="2"><asp:label id="lblerror" runat="server" text="" forecolor="red"/></td>         </tr>         <tr>             <td class="normal" colspan="2">                 <asp:button id="btncancel" runat="server" text="cancel" onclick="btncancel_click" cssclass="medium" />                 <asp:button id="btnupload" runat="server" text="upload" onclick="btnupload_click" cssclass="medium" />             </td>         </tr>     </table> </asp:content> 

it used work fine, now, , without apparent change code/design, both "upload" , "cancel" buttons no longer work.

putting breakpoint in codebehind's page_load() method shows called when page loaded, , not when button pressed. similarly, putting breakpoint in "btnupload_click" event shows never called.

this not working both on own development machine , on client's server (both when browsing servers page machine , server itself).

it's important stress that, between working , not working, 90% sure nothing has changed in regards code.

any appreciated, customer rightly anxious - , i'm clueless what's causing it!

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edit #1

here's codebehind 1 of buttons:

protected void btnupload_click(object sender, eventargs e)     {         if (dataaccess.checkifmassuploadalreadyexists(fufilename.filename))         {             lblerror.text = "a file specified name exists within system.";             return;         }         else         {             try             {                 uploadfile();             }             catch(exception ex)             {                 lblerror.text = ex.message;// +"\nusername:" + system.web.httpcontext.current.user.identity.name;                 return;             }         }     } 

.

here's reason.. , it's annoying reason too!

this:

<script type="text/javascript" src="../help/helppopup.js" /> 

should this:

<script type="text/javascript" src="../help/helppopup.js"></script> 

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whoever decided script tag needs treated differently every other html tag, needs locked in room justin bieber.