"auto-dnssec maintain;" and key "missing or inactive and has no replacement"

[Stephane Bortzmeyer]

On Fri, Jul 26, 2013 at 03:37:46PM +0200,
 Stephane Bortzmeyer <bortzmeyer at nic.fr> wrote 
 a message of 19 lines which said:

> Apparently, it worked without it but, when you use it, there is no
> longer this undecipherable warning.

Actually, it reappeared:

28-Jul-2013 23:19:29.824 zone example/IN (signed): Key example/RSASHA256/1159 missing or inactive and has no replacement: retaining signatures.

So, as soon as you have only one key, you have the problem :-(