I think (based on my own test your computer might have a different table)
that your numbers are wrong
ü:0081
however cout<<"\u0081" gave me an error however cout << "\u00FC" didn't but gave me a wrong character (a superscript n ⁿ or using the format tags n)
in that case Ö:99
to correct the error I used wcout<<wchar(0x0081)<<endl;