Doesn't recognise configured wishes

Apple magic trackpad, Ubuntu 12.04, Gnome3. One and two-finger tapping and scrolling is working fine without Ginn; I am attempting to configure app-specific gestures.

Ginn isn't applying any of the wishes configured in wishes.xml. From its output it is capturing the gestures fine, but is not applying any of the actions.

Using the sample config file:

<ginn>
  <applications>
    <application name="Terminal">
      <wish gesture="Drag" fingers="3">
        <action name="termpgdown" when="update">
          <trigger prop="delta x" min="20" max="80"/>
          <key modifier1="Control_L">Page_Up</key>
        </action>
      </wish>
      <wish gesture="Drag" fingers="3">
        <action name="termpgup" when="update">
          <trigger prop="delta x" min="-80" max="-20"/>
          <key modifier1="Control_L">Page_Down</key>
        </action>
      </wish>
    </application>
  </applications>
</ginn>

I get the output below, but no actions take place.

ginn
 applications
  application
   wish
    action
     trigger
     key
   wish
    action
     trigger
     key

Gesture type 0 started
 attr device id=32144
 attr timestamp=4723180
 attr root window id=182
 attr event window id=182
 attr child window id=182
 attr focus x=765.000000
 attr focus y=481.000000
 attr gesture name="Drag,touch=3"
 attr touches=3
 attr boundingbox x1=-464.000000
 attr boundingbox y1=-231.000000
 attr boundingbox x2=4296497166963830408871936.000000
 attr boundingbox y2=202.000000
 attr position x=577.000000
 attr position y=-69.666664
 attr delta x=0.000000
 attr delta y=0.000000
 attr velocity x=0.000000
 attr velocity y=0.000000
 attr touch 0 id=358.000000
 attr touch 0 x=-464.000000
 attr touch 0 y=-180.000000
 attr touch 1 id=359.000000
 attr touch 1 x=564.000000
 attr touch 1 y=-231.000000
 attr touch 2 id=360.000000
 attr touch 2 x=1631.000000
 attr touch 2 y=202.000000
Gesture type 0 updated
 attr device id=32144
 attr timestamp=4723191
 attr root window id=182
 attr event window id=182
 attr child window id=182
 attr focus x=765.000000
 attr focus y=481.000000
 attr gesture name="Drag,touch=3"
 attr touches=3
 attr boundingbox x1=-496.000000
 attr boundingbox y1=-233.000000
 attr boundingbox x2=1599.000000
 attr boundingbox y2=198.000000
 attr position x=542.333313
 attr position y=-69.000000
 attr delta x=-34.666687
 attr delta y=0.666664
 attr velocity x=-3.151517
 attr velocity y=0.060606
 attr touch 0 id=358.000000
 attr touch 0 x=-496.000000
 attr touch 0 y=-172.000000
 attr touch 1 id=359.000000
 attr touch 1 x=524.000000
 attr touch 1 y=-233.000000
 attr touch 2 id=360.000000
 attr touch 2 x=1599.000000
 attr touch 2 y=198.000000
 --ActiveApp Terminal
Gesture type 0 updated
 attr device id=32144
 attr timestamp=4723203
 attr root window id=182
 attr event window id=182
 attr child window id=182
 attr focus x=765.000000
 attr focus y=481.000000
 attr gesture name="Drag,touch=3"
 attr touches=3
 attr boundingbox x1=-518.000000
 attr boundingbox y1=-233.000000
 attr boundingbox x2=4296497166963830408871936.000000
 attr boundingbox y2=195.000000
 attr position x=518.333313
 attr position y=-69.333336
 attr delta x=-24.000000
 attr delta y=-0.333336
 attr velocity x=-2.000000
 attr velocity y=-0.027778
 attr touch 0 id=358.000000
 attr touch 0 x=-518.000000
 attr touch 0 y=-170.000000
 attr touch 1 id=359.000000
 attr touch 1 x=499.000000
 attr touch 1 y=-233.000000
 attr touch 2 id=360.000000
 attr touch 2 x=1574.000000
 attr touch 2 y=195.000000
 --ActiveApp Terminal
(etc)

These delta x values are within the configured range for the PgDown action, but it does not seem to be called.