The relevant facts in the instant appeal are as follows: Having been adjudicated as delinquent by reason of his commission of a burglary, B. S. L. was placed on probation. After B. S. L.’s seventeenth birthday, he allegedly committed another burglary. However, no petition to revoke B. S. L.’s probation pursuant to OCGA § 15-11-42 (b) was filed. Instead, a delinquency petition was filed alleging that B. S. L.’s commission of the subsequent burglary was a delinquent act in *171that it was a violation of his probation. See OCGA § 15-11-2 (6) (B). The juvenile court found B. S. L. to be delinquent by reason of the commission of a designated felony act and, after determining that restrictive custody was required pursuant to OCGA § 15-11-37 (c), entered a dispositional order in conformity with OCGA § 15-11-37 (e). It is from that order that the State appeals.
The State’s contention is that the juvenile court erred in failing to enter its dispositional order in compliance with OCGA § 15-11-37 (f). OCGA § 15-11-37 (f) provides: “When the order is for restrictive custody in the case of a youth found to have committed any designated felony act and such youth has been found by a court to have committed a designated felony act on a prior occasion, regardless of the age of the youth at the time of commission of such prior act, the order of the court shall” impose a mandatory initial 18-month period of confinement in a youth development center.
“The juvenile court shall not have jurisdiction to initiate any new action against an individual for acts committed after he has reached the age of 17 years.” (Emphasis supplied.) OCGA § 15-11-5 (d). Thus, although the violation of probation may constitute a “delinquent act” in and of itself, a violation of probation which occurs after the juvenile’s seventeenth birthday will not authorize the initiation of a new delinquency petition against the juvenile. The juvenile court’s jurisdiction would extend only to revoking the juvenile’s probation for his previous adjudication of delinquency. The juvenile court “shall have exclusive original jurisdiction over juvenile matters and shall be the sole court for initiating action: Concerning any child . . . [w]ho has been placed under the supervision of the court or on probation to the court; provided, however, that such jurisdiction shall be for the sole purpose of completing, effectuating, and enforcing such supervision or a probation begun prior to the individual’s seventeenth birthday. . . .” OCGA § 15-11-5 (a) (1) (F).
It follows that, if a probation revocation petition had been filed in the instant case, then the juvenile court would have been authorized to enter a dispositional order pursuant to OCGA § 15-11-37 if the original burglary was shown to be a “designated felony act.” “[I]t is permissible to subject probation violators to the sentence which might have originally been imposed upon them in lieu of probation, or to impose a greater sentence than that originally given. [Cit.]” In the Interest of B. N. D., 185 Ga. App. 906, 907 (366 SE2d 187) (1988). “However, no petition to revoke [B. S. L.’s] probation was ever filed in the juvenile court. Indeed, it appears that only a petition of delinquency was filed, alleging [B. S. L.] had committed the [delinquent act of violating his probation by perpetration of another burglary].” In re B. C., 169 Ga. App. 200, 201 (311 SE2d 857) (1983).
“Jurisdiction over the subject matter of a case cannot be con*172ferred by agreement or consent. [Cits.] A judgment rendered by a court without jurisdiction of the subject matter is a nullity and is subject to reversal by the appellate courts on their own motion. [Cit.]” Barland Co. v. Bartow County Bd. of Tax Assessors, 172 Ga. App. 61, 62 (322 SE2d 316) (1984). Thus, the juvenile court in the instant case clearly did not err in failing to impose a mandatory 18-month period of confinement against B. S. L. This is true because the juvenile court had no subject matter jurisdiction to adjudicate B. S. L. to be delinquent by reason of his alleged commission of a burglary after his seventeenth birthday or to enter any dispositional order based on such a finding. Accordingly, those void orders are hereby reversed.
Decided June 25, 1991. Thomas J. Charron, District Attorney, Amy H. McChesney, Assistant District Attorney, for appellant. Derek H. Jones, for appellee. Brian S. Lipscomb, pro se.Judgment reversed.
Banke, P. J., and Beasley, J., concur.