title: R - plotly error object ... not found
body: <p>I try to run a sample line with iris data set gives object '...' not found error. 
  Is there any I need to check specific in my environment? </p>
  
  <pre><code>library(plotly)
  p &lt;- plot_ly(iris, x = Petal.Length, y = Petal.Width,color = Species, mode = "markers")
  </code></pre>
  
  <blockquote>
    <p>Error in plot_ly(iris, x = Petal.Length, y = Petal.Width, color = Species,  : 
      object 'Petal.Length' not found</p>
  </blockquote>