HTTP ERROR 401 must authenticate

URI:/service/home/michal.krystkowiak@put.poznan.pl/Briefcase/Materia%C5%82y%20do%20pobrania/Aktualny_semestr/Wsp%C3%B3%C5%82czesne%20technologie%20poprawy%20jako%C5%9Bci%20zasilania
STATUS:401
MESSAGE:must authenticate
SERVLET:UserServlet