c# - Cannot get image file at server side from File Uploader in asp.net -

i have html control fileuploaderand add runat="server" access @ server side, don't want user asp:fileuploader because of bad css style in bootstrap

<span> <input type="file" runat="server" id="file_upload" /> </span> 

now need image html fileuploder save in database got example code google image fileuploader as

byte[] imgbyte = null; if (file_upload.postedfile != null) {     httppostedfile file = file_upload.postedfile;     imgbyte = new byte[file.contentlength];     file.inputstream.read(imgbyte, 0, file.contentlength);  } 

but when examine using breakpoint compiler not enter if body because of null vaule

i used this

 scriptmanager.getcurrent(this).registerpostbackcontrol(this.file_upload); 

in form_load event due using asp:updatepanel

but didn't file (image) fileuploader

i need solve issue..

thanks in advance.

edit:

when remove asp:updatepanel can access file select.

and use

<triggers>       <asp:postbacktrigger controlid="file_upload" />    </triggers> 

solution:

mistakenly used fileuploader's id , following @suprabhat's suggestion change

<triggers>               <asp:postbacktrigger controlid="btncreate" />            </triggers> 

and working fine..

try adding enctype="multipart/form-data" attribute form element.