title: Lattice wireframe does not show mesh
body: <p>I want to plot a 3D graph with lattice. I managed to do a 3D scatterplot, but if I try to plot my graph with the wireframe function the graph appears empty.</p>
  <p><a href="https://i.stack.imgur.com/xQF8q.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/xQF8q.png" alt="enter image description here" /></a></p>
  <p>This is a part of my data with which I could reproduce my issue:</p>
  <pre><code>    structure(list(z = c(35.6848570203496, 20.6910550942398, 36.2505636561432, 
      38.9791450251443, 12.9514876234809, 10.0549459964936, 7.1604652315673, 
      14.681581323841, 29.7104179049907, 8.4814778127832), y = c(21.72, 
      21.72, 21.72, 21.72, 3.57, 3.57, 4.83, 4.83, 4.83, 4.83), x = c(22L, 
      136L, 79L, 23L, 34L, 22L, 16L, 66L, 30L, 1L)), row.names = c(NA, 
      -10L), class = c(&quot;tbl_df&quot;, &quot;tbl&quot;, &quot;data.frame&quot;))
  </code></pre>
  <p>This is my code:</p>
  <pre><code>    wireframe(z~x*y,df, scales=list(arrows=FALSE))
  </code></pre>