What is the burden of an appellant to provide an adequate record to permit review of a claimed error?

"It is axiomatic that it is the burden of the appellant to provide an adequate record to permit review of a claimed error, and failure to do so may be deemed a waiver of the issue on appeal. [Citations.]" (People v. Akins (2005) 128 Cal.App.4th 1376, 1385.) Moreover, we presume "that official duty has been regularly performed." (Evid. Code, 664.) And error will not be presumed from a silent record. (Denham v. Superior Court (1970) 2 Cal.3d 557, 564.) Thus, we reject defendant's claim that there was no dialogue from which the court might discern defendant's understanding.