You see, I like many people probably have more than one acct and set of Google calendars. In my case, I teach and have class calendars for my classes. But I share the calendars with both of my own accounts so when I'm logged on as either person, I can edit the calendars. Well, it turns out I was trying to add a calendar that didn't belong to the proper account. In other words, I kept trying to fix Acct. B when the calendar actually belonged to Acct. A. When I finally realized the error, I went into Acct. A's online calendars, made sure the calendar was visible there, and resynced the acct on my phone. Presto, all set.
And as a reminder, the way Google Calendars work on Android is that it syncs whatever calendar you had showing in your online Google Calendar at the time of the initial sync. If you add new calendars, they won't show up in Android unless you clear and re-add the account.