For some reason I've also found this, but there is a way around it.
1. Add a register asp.net tag to register the controls location.
2. Manually enter the asp.net tag to create the required control, in the HTML.
3. Check that the code behind file has had the control also added.
If you need any examples, check out DNN's core and modules as they are littered with examples on how to do this.
Hope this helps,
Stewart WalkerByte Information Technology