Postal code 1010 Cité administrative de l'État - Rijksadministratief Centrum
is no more in use since 30/09/2016 

see https://www.socialsecurity.be/portail/glossaires/dmfa.nsf/ConsultFrImprPDF/93334AEC94585C74C1258CFB002D4547/$FILE/VersComplDMFA254_F.pdf (page 398)

Also not pass the validation tools of the universal postal service provider