Solving for error when installing Role Center and Enterprise Portal AX 2009

This error ate my head for many hours before I was able to solve it.

I had this error:

No .NET Business Connector session could be found.

When installing Role Center and Enterprise Portal. Make sure you have done following:

1. AX Client and Business Proxy Connector accounts are pointing to appropriate AOS.
2. If you have installed SP1 for AOS, then you need to have it installed for Client and BC Proxy also.
3. Compile SysDevelopmentProxy class from Application Object Tree. If not possible, compile whole application.

Third step is solution for above problem. Very bad.

Also, thanks to Iulian Cordobin on dynamicsuser.net for the solution.