https://www.mediawiki.org/wiki/Extension:CrossReference

Hello. The Extension:CrossReference is listed as installed and working on Special:Version page.
When I try to see how it works in User's Sandbox the extension does not work.

Sandbox does not recognize commands:
<twocolumns>
<break>
</twocolumns>

the code used from example section on extension page:
...
Figure <xr id="fig:Agent_LifeCycle#1"/> illustrates the standard agent's life-cycle.
...
Figure <xr id="fig:Agent_LifeCycle#2"/> illustrates the finer agent's life-cyle,
...
<figure id="fig:Agent_Life_Cycle">
<twocolumns>
<subfigure>
[[Image:Standard Agent LifeCycle.png|frame|<caption>Standard Agent's Life-Cycle</caption>]]
</subfigure>
<break>
<subfigure>
[[Image:Finer Agent LifeCycle.png|frame|<caption>Finer Agent's Life-Cycle</caption>]]
</subfigure>
</twocolumns>
<center><small><caption>Life Cycles of Agent</caption></small></center>
</figure>
...

I believe that there is another extension is missing to make Extension:CrossReference work correctly.
Thank you in advance for your time for taking attention to this matter.