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

[Stephane Bortzmeyer]

On Wed, Jul 24, 2013 at 09:58:08AM -0700,
 David Newman <dnewman at networktest.com> wrote 
 a message of 89 lines which said:

> Not sure if this is the problem, but have you tried with
> "managed-keys-directory" in options instead of "key-directory"?

I just tried, and same warning:

26-Jul-2013 08:53:43.637 running
26-Jul-2013 08:53:43.637 zone example/IN (signed): loaded serial 2013071800
26-Jul-2013 08:53:43.637 zone example/IN (signed): receive_secure_serial: unchanged
26-Jul-2013 08:53:43.637 zone example/IN (signed): sending notifies (serial 2013071800)
26-Jul-2013 08:53:43.637 zone example/IN (signed): reconfiguring zone keys
26-Jul-2013 08:53:43.721 zone example/IN (signed): next key event: 26-Jul-2013 09:03:43.637
26-Jul-2013 08:53:43.805 zone example/IN (signed): Key example/RSASHA256/1159 missing or inactive and has no replacement: retaining signatures.
26-Jul-2013 08:53:48.638 zone example/IN (signed): sending notifies (serial 2013071802)