What are the implications of a parole officer revoking a convicted sex offender's parole because he failed to enter a sex offender program?

1 MacNab argues for the first time on appeal that: (1) the parole officer violated his constitutional rights by revoking his parole when he failed to enter a sex offender program as a special condition of his parole; and (2) he was denied equal protection under the Fourteenth Amendment because his "privileged" visitation with his wife was terminated based on her refusal to present photo identification, although she allegedly continued "basic" visitation with a fellow prisoner without presenting photo identification. We decline to address these arguments because MacNab did not raise them before the district court. See United States v. Childs, 944 F.2d 491, 495 (9th Cir.1991).