LaTeX; Refer in one document-class to chapters in another document-class

Question

I want to include an article (with documentclass: IEEEtran) into a report (with another, company specific, documentclass). I want to refer in the article (myarticle.pdf) to the ten appendices of the report. I tried it with include pdf:

\documentclass{Report}  
\usepackage{pdfpages}  
\begin{document}   
Report  
includepdf{myarticle.pdf}%refer in this article to ~\ref{app:req}  
\appendix  
\chapter{Requirements}% The first appendix  
\label{app:req}  
\end{document}  

The problem is that with pdfpages the article can not refer to the appendices of the report. How can I solve this?