Hi everyone, I'm making a nice circo plot for my research and I'm having a trouble trying to plot axes for several stacked data tracks, so I need to place the axes on front with the Z = 10 coordinate. In the documentation for Axes and background http://circos.ca/documentation/tutorials/quick_start/axes_and_backgrounds/lesson, is pointed out an option to draw axes inside a bare plot block <plot> not indicating a specific type of plot, just a bare plot block. The problem is when I run the .conf file, the prompt says that I need to specify the type of plot to be draw... weird thing since the documentation says the opposite...

This is my code:

<plot>
r0        = 0.83r
r1        = 0.98r
z = 10
<axes>
<axis>
position = 0.5r
color     = grey
thickness = 2
</axis>
<axis>
position = 0.166666r
color     = grey
thickness = 2
</axis>
<axis>
position = 0.833333r
color     = grey
thickness = 2
</axis>
</axes>
<backgrounds>
<background>
color = vvlgrey
</background>
</backgrounds>
</plot>

The error is:

 *** CIRCOS ERROR ***

  You must specify a type for a track. Choose one of
  [scatter,line,histogram,heatmap,highlight,tile,text,connector].

Hope you can help me, if you need more information just ask and I'll be glad to provide it