flashing Cyanogenmod 9 "Backup and Restore" don't appear in boot menu

[maplewood]

I'm trying to flash CyanongenMod 9 on my Incredible.

I have ROM manager (Pro) installed.
I have DL'd

• update-cm-9.0.0-RC0a4-inc-UNOFFICIAL-signed.zip
• gapps-ics-20120317-signed.zip

Both zips are in the root directory of the SD card.

The instructions available at Cyanogenmod 9 for Droid Incredible [Installation Guide] and elsewhere state that you should boot into recovery and do a backup and restore. When I boot into Recovery I have a choice of

• FASTBOOT
  • Bootloader
  • Reboot
  • Reboot Bootloader
  • Powerdown

Or I can select "Bootloader" and have the choices of

• HBOOT (with submenu)
• Fastboot
• Recovery (this just takes me back to "Fastboot" menu above)
• Clear Storage
• Simlock
• Factory Reset

I get these menus regardless of whether I boot into Recovery manually (volume button/power) or whether I select "Install from SD Card" in Rom Manager.
(No "backup and Restore") choice. (Rom manager asks me to press "OK" to boot into CWM Rocovery).

I have done a backup with ROM manager and with BackupEverything so perhaps my backup is available.

But when I try to Install the rom I end up at the boot screen with no option that seems to install the CYN-09.

Clearly I'm missing something really obvious. Any clues?