Setting disable-while-typing from touchpad settings has no effect

1) Ubuntu 12.04.4 LTS
2) gnome-control-center: Installed: 1:3.4.2-0ubuntu0.13.1
3) I expected the touchpad to be disabled while I am typing.
4) The touchpad is not disabled: the text point jumping to the cursor location when my wrist bumps the touchpad while I am typing.
Viewing org.gnome.settings-daemon.peripherals.touchpad in dconf-editor shows that disable-while-typing is not set, although the option is set in Mouse and Touchpad settings in gnome control center (see screenshot)

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: gnome-control-center 1:3.4.2-0ubuntu0.13.1
ProcVersionSignature: Ubuntu 3.8.0-37.53~precise1-generic 3.8.13.18
Uname: Linux 3.8.0-37-generic x86_64
ApportVersion: 2.0.1-0ubuntu17.6
Architecture: amd64
Date: Fri Mar 21 21:21:56 2014
ExecutablePath: /usr/bin/gnome-control-center
InstallationMedia: Ubuntu 12.04.3 LTS "Precise Pangolin" - Release amd64 (20130820.1)
MarkForUpload: True
ProcEnviron:
 PATH=(custom, no user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: gnome-control-center
UpgradeStatus: No upgrade log present (probably fresh install)
XsessionErrors: (compiz:18958): GConf-CRITICAL **: gconf_client_add_dir: assertion `gconf_valid_key (dirname, NULL)' failed
usr_lib_gnome-control-center:
 activity-log-manager-control-center 0.9.4-0ubuntu3.2
 deja-dup 22.0-0ubuntu4
 gnome-bluetooth 3.2.2-0ubuntu5.1
 indicator-datetime 0.3.94-0ubuntu2