Vb.net - Fill / Update Row In Gridview When A Textbox Loose Focus

I have the following gridview that is inside an updatepanel:

<asp:UpdatePanel ID="UpdatePanel1" runat="server">
<ContentTemplate>
<asp:Button ID="ButtonAdd" runat="server" OnClick="ButtonAdd_Click" Text="Novo Artigo" />
<asp:GridView ID="Dados" runat="server" AutoGenerateColumns="False" CssClass="Grid">
<Columns>
<asp:TemplateField HeaderText="Artigo">
<ItemTemplate>
<asp:TextBox ID="Artigo" runat="server"></asp:TextBox>
<asp:ModalPopupExtender ID="ModalPopupExtender1" runat="server"
TargetControlID="Artigo"
PopupControlID="PanelArtigos"
>
</asp:ModalPopupExtender>
</ItemTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="Descrição">
<ItemTemplate>
<asp:TextBox ID="Descricao" runat="server" Width="300px"></asp:TextBox>
</ItemTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="IVA">
<ItemTemplate>
<asp:TextBox ID="IVA" runat="server" Width="40px" Enabled="false"></asp:TextBox>
</ItemTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="Pr. Unit.">
<ItemTemplate>
<asp:TextBox ID="PU" runat="server" Width="50px"></asp:TextBox>
</ItemTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="% Desc.">
<ItemTemplate>
<asp:TextBox ID="Desconto" runat="server"></asp:TextBox>
</ItemTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="UN">
<ItemTemplate>
<asp:TextBox ID="UN" runat="server" Width="50px" Enabled="false"></asp:TextBox>
</ItemTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="Quant.">
<ItemTemplate>
<asp:TextBox ID="Quantidade" runat="server" Width="50px"></asp:TextBox>
</ItemTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="Total Liquido">
<ItemTemplate>
<asp:TextBox ID="TotalLiquido" runat="server" Enabled="false"></asp:TextBox>
</ItemTemplate>
</asp:TemplateField>
<asp:TemplateField>
<ItemTemplate>
<asp:LinkButton ID="RemoveArtigo" runat="server" OnClick="RemoveArtigo_Click">Remover
</asp:LinkButton>
</ItemTemplate>
</asp:TemplateField>
</Columns>
<HeaderStyle Font-Size="Small" />
<RowStyle Font-Size="Small" CssClass="grid" />
</asp:GridView>
</ContentTemplate>
</asp:UpdatePanel>

As you can see, i have some textbox's. When i change a value in a textbox, for example, the Desconto value, and leave that textbox, i want that the row where i am to be updated, using the new value present in the textbox. It's like a TextChanged or onBlur, but inside the update panel it's not working. what is the best way to do it? I am using VB.NET. When adding the OnTextChanged="Desconto_TextChanged" i receive this compilation error: Compilation Error Description: An error occurred during the compilation of a resource required to service this request. Please review the following specific error details and modify your source code appropriately. Compiler Error Message: BC30456: 'Desconto_TextChanged' is not a member of 'ASP.index_aspx'. Source Error:

Line 204:
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Line 206:
Line 207:
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Source File:
C:inetpubwwwrootFacturasFacturasindex.aspx
Line: 206