error after uploading on server Pin

Hi
I'm getting error in "using Qse;" please help me.
locally it's working but after uploading on server not working.

I have created some functions in .cs file with namespace Qse in
App_Code folder in asp.net web application.
and in .aspx.cs trying to accees like this..

.
.
using Qse;//coming error error not able to find Qse
.
.
public partial class _Default : System.Web.UI.Page
{
Dbconnect DC = new Dbconnect();
protected void Page_Load(object sender, EventArgs e)
{

}
.
.
.


thanks in advance.....

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