4 family member got visa 1 pending

[fazlehaque]

hello
my brother recently got visa with his wife and 2 son(My sister is an us citizen she was the petetioner,brother was principal beneficiary and his and 3 sons are derivative beneficiary).But his eldest son who is 21 now didnt receive his passport(he became 21 after immigration interview,His passport is in us embassy now).They said its on adminstrative processing.
Any idea about this situation?

thanks

[mehta_agm1979]

possibly they are administering his cspa elligibility.