Putting \ref inside \section - Top of page problem

[Bruno-Eijs]

I have some sections that refer to theorem numbers in their titles. The title then prints it out fine, but at the top of the page the section title is printed again and here the theorem number is just question marks.

Example code:

\section{The proof of Theorem \ref{thm:theorem} }

I've tried replacing it with

\section{The proof of Theorem \texorpdfstring{\ref{thm:theorem}}{TEXT} }

but that doesn't help. Maybe there is a work around like storing the reference as a sort of variable first, but I'm not sure how to go about this. Many thanks in advance.