[c-nsp] getting a 1721 to boot a new image

[Ed Ravin]

I must be doing something stupid.  I'm trying to upgrade a Cisco 1721
at a remote site.  It has a nice big flash, so I downloaded the new IOS
without deleting the old one.  The flash directory looks like this:

Router#dir flash:
Directory of flash:/

    1  -rw-     5860776                    <no date>  c1700-y-mz.123-10.bin
    2  -rw-        5254  Nov 13 2006 18:25:25 -05:00  cfg20061110.bak.cfg
    3  -rw-     5944480  Feb 27 2007 18:22:23 -05:00  c1700-y-mz.123-22.bin
    4  -rw-        6061  Feb 27 2007 18:27:58 -05:00  cfg2007old.cfg

33292284 bytes total (21475452 bytes free)

Previously, there were no "boot system" entries in the config file.  I
added them as follows:

Router#show run | inc boot
boot-start-marker
boot system flash flash:c1700-y-mz.123-22.bin
boot system flash flash:c1700-y-mz.123-10.bin
boot-end-marker

But this was ignored - it still booted the first image in flash, the 123-10
image.  I also tried "boot system flash c1700-y-mz.123-22.bin", to no avail.

I found an errata about "boot system flash" requiring a colon as in
"flash:", but that was for 12.2(4)YH, and doesn't seem to apply for
using filenames.

DId I miss something obvious?  Why does the router seem to be ignoring
the boot commands?