ASP.NET and Rhoelements

Has anyone been successful at using ASP.NET with Rhoelements? (Not ASP.NET MVC).

I'm finding that the pages render fine, but postbacks aren't working. Digging into it, it looks like ASP.NET is not injecting the hidden elements it uses to do postbacks (__EVENTARGUMENT & __EVENTTARGET).

Thanks,

Josh