I had the same problem today, but it is in C#.
all you need to do is declare the control with it's name instead of declaring it as a user control. For instance, in my case:
public class sniff : System.Web.UI.UserControl {
code here
}
is then instantiated on my page thus:
protected sniff ctrl_Sniff;
I had tried to do it this way unsuccessfully:
protected System.Web.UI.UserControl ctrl_Sniff;
HTH,
~ Knute