slytherin house crest
    First name: Draco
    Middle name: Lucious
    Nick name: none
    Last name: Malfoy
    Blood status: pure-blood
    Is not a prefect
    Is not expelled
    Is not a member of inquisitorial squad
    Draco Malfoy

    ... is not pure-blood.

    Only pure-bloods can be added to inquisitorial squad from the Slytherin house.

    Choose another (pure-blood) student.

    There are already two students appointed as prefects from the house.

    You have to revoke one in order to appoint the new one.

    There is already one girl appointed as prefect from the house.

    Revoke her in order to appoint the new girl or choose a boy as second prefect.