Loading a web user control from different assembly

Question

If I load a web user control in an assembly from different assembly, the controls in the user controls dont get intialized. I need to explicitily intialize them.

For instance, I create a user control(TestControl ) in assembly(AssemblyName) with label in it. And I use it in different assembly as below

<%@ Register TagPrefix="uc1" Namespace="Namespace" Assembly="AssemblyName" %>

<uc1:TestControl ID="Test" runat="server"/>

The label in the user control in the referred assembly always remains NULL. I need to add it at runtime in the control. Do i need to take care of anything else or am I missing anything.

Any help would be appreciated.

Thanks in advance.