Cannot insert a SP People Picker in an asp panel or view

I can using the following control on a aspx page or inside a table. However, I got an error of "no object or instance defined" in design time when I added it to a panel, update panel or view.

<SharePoint:PeopleEditor ID="myPicker" runat="server" SelectionSet="User"
AllowEmpty="false" Rows="1" PlaceButtonsUnderEntityEditor="false"
MultiSelect="false" AutoPostBack="false"
Width="250px" BackColor="#DFEFFF" BorderStyle= "NotSet" Font-Names="Verdana"
style="font-size: small" />

I just wonder if there is a work around because I need to place the control in the asp panel or view.

Many thanks.