the first time that Alfaro has waived, rather than forfeited, his claim that the district court improperly imposed the sixteen-level enhancement because Alfaro acquiesced at the February 5, 2004 sentencing hearing to the district court’s finding that the probation officer had properly calculated his offense level. Prior to the sentencing hearing, Alfaro objected to the enhancement on the ground that he was a juvenile when convicted of the Virginia offense. At the sentencing hearing, Alfaro withdrew this objection after being provided with proof that he was prosecuted as an adult. He did not, however, waive the entirely different objection that he was not convicted of a “crime of violence.” See United States v. Aguilar-Delgado, 120 Fed.Appx. 522, 523 n. 2 (5th Cir.2004) (unpublished) (<HOLDING>). Additionally, Alfaro's failure to object to
holding that defendants have a federal constitutional right to make a collateral attack on a prior conviction only when that conviction was obtained without the assistance of counsel holding that for sentencing purposes the government does not need to allege a defendants prior conviction or prove the fact of a prior conviction where that fact is not an element of the present crime holding that application of the modified categorical approach did not establish a covered conviction where the judgment of conviction did not contain the factual basis for the crime holding that the withdrawal of an unrelated factual objection to a prior conviction did not waive the defendants right to plainerror review of his claim that this same conviction was not for a crime of violence under  2l12 holding that  215 is categorically a crime of violence for purposes of ussg  2l12