title: How do i get the graph to draw a line for constant 0 values using amcharts?
body: <p>I'm showing network throughput and disk io's in a graph.
  But when there is no activity. 0 get's reported. 
  The balloon shows me 0 but the line is not being drawn.
  it looks like the grid is on top but if I turn the grid off the line still isn't there.</p>
  
  <p>if I make line-thickness 2, I can see it but then the line changes thickness between 0 value and non 0 value. from 1px  to 2 px.</p>
  
  <p>i can't find anything in the documentation about this.
  Any clue?</p>