Html element from a Tab

I was able to acces an HTML element from my c# code this way:
Page.Request.Form["Name"].ToString(), where name was an html element:
<input id="Name" style="z-index: 102;" type="file">
Now that I put this html inside a Tab containe (subpanel) the Page.Request.Form["Name"].ToString() fail, actually while I was debugging I could not find this element inside Page.Request.Form.
Any idea? maybe there is another way of accesing the Html element from my c# code?
Thanks,
Eli
 
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