Erreur sur CMap

Bonjour,
je veux utiliser une CMap...
Code:

1 2 3 4 5 6 7 8 9 10 CMap<CString, CString&, CString, CString&> h; h.InitHashTable(100); h.SetAt(CString("one"),CString("ti")); h.SetAt(CString("two"),CString("tt")); int val;CString out; h.Lookup(CString("one"), out);
et j'ai l'erreur suivante :

Citation:

Compiling...
Services.cpp
c:\program files\microsoft visual studio\vc98\mfc\include\afxtempl.h(129) : error C2440: 'type cast' : cannot convert from 'class CString' to 'unsigned long'
No user-defined-conversion operator available that can perform this conversion, or the operator cannot be called
c:\program files\microsoft visual studio\vc98\mfc\include\afxtempl.h(1324) : see reference to function template instantiation 'unsigned int __stdcall HashKey(class CString &)' being compiled
Error executing cl.exe.
Creating browse info file...

DemoCityRama.exe - 1 error(s), 0 warning(s)

Merci de toute aide