PostedFile is coming NULL, Iam uploading the file then also coming NULL [Resolved]

<input id="UpBattery" runat="server" style="width: 286px" type="file" visible="false" />
                        <asp:Button ID="Button1" runat="server"  OnClick="Button1_Click" Text="Upload" Visible="False" />

protected void Button1_Click(object sender, EventArgs e)
        {
            DataTable dtgridstc = (DataTable)ViewState["GridTab"];
            DataTable dtGrid = dtgridstc.Clone();
            lblError.Text = "";
            lblSuccess.Text = "";
            try
            {
                if (UpBattery.PostedFile.FileName.Length >= 1)
                {
                    HttpPostedFile excelFile = UpBattery.PostedFile;
                    if (excelFile.FileName.ToUpper().EndsWith(".XLS") == false)
                    {
                        lblError.Visible = true;
                        lblError.Text = "This is not a valid Battery Details File[Not an MS Excel File]";
                        return;
                    }

[Resolved]