ABO Typing 

He has used, it's Rh +ve

Landsteiner’s Law: If an agglutinogen (antigen) is present on the red cell membrane, the corresponding agglutinin (antibody) must be absent in the plasma. And conversely, for the ABO blood group system, if the agglutinogen is absent in the red cells, the corresponding agglutinin must be present in the plasma

@@Nevmesha that is not true, without any reaction even reagents using can give agglutination,so to exclude that we use control