In a personal jurisdiction action, how have courts dealt with the issue of ineffective service?

In his opening brief, plaintiff does not discuss the trial court's ruling that service was ineffective. Plaintiff concedes his failure but claims the issue "is moot" because he could serve defendants again. Regardless of whether he could re-serve defendants, an appellant's failure to raise an issue in his or her opening brief waives that challenge. (Roehl v. Ritchie (2007) 147 Cal.App.4th 338, 352, fn. omitted.) We affirm the judgment on this basis alone without addressing the personal jurisdiction issue.