why doesn't this visNetwork in R show edge
<p>I'm exploring visNetwork and can't figure out why this one doesn't show edge</p>

<pre><code>library(visNetwork)
nodes=data.frame(node=c('m1','m2','n1','n2'))
a=data.frame(x=c('n1','n2'),y=c('m1','m2'))
links=a%&gt;% group_by(x,y)%&gt;%tally()
visNetwork(nodes, links)
</code></pre>