title: "Incorrect Plot" label in ggpairs
body: <p>I have a simple question.</p>
  
  <p>How can I get totally blank spaces in the upper panel of a matrix using ggpairs?</p>
  
  <p>I am using this code:</p>
  
  <pre><code>ggpairs(iris, columns = 2:4, title = "[1989]",
          upper = list (continuous = "blanck"), lower = list(continuous = "points"), diag = list(continuous = "blanck"),
          axisLabels = "show",
          legends = TRUE)
  </code></pre>
  
  <p>I just want the 3 plots on the lower panel, but the code print grids and the label "Incorrect Plot" both in the diagonal and upper panel.</p>
  
  <p>I will appreciate any help!</p>