Numeric extender dosent work probely

picture: http://www.speedyshare.com/zQ65F/numeric.png

Hi what is going wrong, i just follewd a tutorial, but the extender just overrule my textbox inputfield.

<asp:Panel runat="Server" ID="pnlPopUp" CssClass="pnlBackGround" ><div class="inner" ><table border="0" ><br /><tr><h3>Registrer new device</h3></tr><br /><tr><asp:Label ID="Label2" runat="server" Text=" Number of registration: " Width="150px"></asp:Label><asp:TextBox ID="DeviceCount" runat="server" Width="100px" ></asp:TextBox><ajax:NumericUpDownExtender ID="RegistrationCount" runat="server" TargetControlID="DeviceCount" Minimum="1" Maximum="10" RefValues=""
                                        ServiceDownMethod="" ServiceUpMethod="" TargetButtonDownID="" TargetButtonUpID="" Width="100"></ajax:NumericUpDownExtender></tr>