<asp:TextBox ID="TextBox5" runat="server" Font-Size="12pt" Width="92px">10</asp:TextBox>
<ajaxToolkit:NumericUpDownExtender ID="NumericUpDownExtender1" runat="server"
TargetControlID="TextBox5">
</ajaxToolkit:NumericUpDownExtender>
So... problem is : My TexBox5 becomes very small at width and it doesn't care what width I setup.