Difficulty getting IDiaSymbol::findChildren to return symbols matching wildcard expression

Question

I am struggling to get the ms-pdb Dia interface to return all the symbols matching a wildcard pattern ( i.e. nsRegularExpression in dia2.h - although documentation implies they are not true regular expressions ). However a call like:

hr = diaGlobal->findChildren( SymTagUDT, OLESTR("MyNameSpace::*"), nsRegularExpression, &diaSymbols );

Returns no symbols whereas:

    hr = diaGlobal->findChildren( SymTagUDT, OLESTR("MyNameSpace::ASymbol"), nsRegularExpression, &diaSymbols );

will return MyNameSpace::ASymbol via diaSymbols. This is using VS2008, pdb built using the same compiler on the same machine.

Ultimately the purpose is to quickly find the definitions of all types within a known namespace to build a mini-pdb for deployment to games console. This will be used for runtime data-reflection.