asp:FileUpload control not working on second time

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ASM

Ajax

C#5.0

handler

Hi All,

Asp file upload control not working when i get response from handler. first time its working fine, when i clicked on file upload , i can able to select file but after that nothing happening.
please help to rectify the issue.

<asp:FileUpload runat="server" id="fleupload" />

$('#btn').click(function () {
       
             
                $.ajaxFileUpload({
                    type: 'POST',
                    contentType: "application/json; charset=utf-8",
                    url: 'Handlers/UploadFile.ashx',
                    
                    secureuri: false,
                    dataType: 'text',
                    contentType: "text/html",
                    data: { $('#aid').val() },
                    success: function (data, status) {
                  
                        if (data.length > 0) {
                           
                            alert(data);
                        }
                        else {
                           
                        }
                    },
                    error: function (data, status, e) {
                   
                        if (err.statusText.length > 0) {
                            
                            alert(err.statusText);
                        }
                    }
                });
            }
        }