<include> tag to nest models not working

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Haven't gotten to adding the Plugin/Xacro for the laser yet, but for some reason, using the <include> and <uri> tags within <model> of model.sdf of a Pioneer robot does not seem to yield the import of the Hokuyo Laser.

http://sdformat.org/spec?ver=1.6&elem... Following the documentation here, what I'm doing, seems fine. Any help?

<include>
  <uri>model://hokuyo</uri>
     <pose>0.2 0 0.9 0 0 0</pose>
</include>
<joint name="hokuyo_joint" type="revolute">
   <child>hokuyo::link</child>
   <parent>chassis</parent>
   <axis>
     <xyz>0 0 1</xyz>
     <limit>
        <upper>0</upper>
        <lower>0</lower>
     </limit>
  </axis>
</joint>