Focus + Context with a bullet graph

[prayingmantis]

Hello all, I'm currently working on an application that requires a
"focus + context" bar graph to show the users their usage of a service
over time. I was able to create this quite easily but now I need a
"focus + context" bullet graph to show users where their usages fall
among their peers. I've replaced the bars function with the following
(don't worry about the size calculations):

var usageBars = focusPanel.add(pv.Layout.Bullet)
.data(usagestats)
.orient("bottom")
.width(function() 39000/z.dx)
.left(function(d) (fx(d.billingMonthYear)))
.ranges(function(d){ return [d.sdQ1, d.sdAverage,
d.sdQ3]})
.bottom(1);

How ever this results in an empty focus area. There are no errors
thrown and no other anomalies in what's displayed. Anyone know what
may be going on here?