Ronald Jay Clifton pleaded guilty to counts one and two of an information charging him with conspiracy to commit fraud and securities fraud. Clifton has appealed, raising issues related to the district court’s upward departure from the guideline imprisonment range. In his plea agreement, Clifton waived the right to raise these issues on appeal and the record reflects that the waiver was knowing and voluntary. See United States v. Melancon, 972 F.2d 566, 567-68 (5th Cir. 1992). We caution counsel that the assertion of issues on appeal that are plainly barred by a plea agreement and the failure to explain in briefing why the defendant’s issues are not waived invites the imposition of a sanction. See United States v. Martinez, 263 F.3d 436, 438 (5th Cir. 2001). The appeal is

DISMISSED.