Missing image inside of infobox on pdf creation

[willblatt]

I can't seem to get the image inside the infobox to render.  In the infobox cell, instead of the image I'm getting [[File:|310px|]]

However, all the images in the article show up correctly. 

in the infobox template, the cell for the image looks like:

#if: {{{image|}}} |{{#vardefine:person|{{{image}}}}}

[[File:{{#var:person}}|310px|]]

this is the command I'm running (on Ubuntu 11.04):

$ mw-render --config="http://blattmans.com/" --writer=rl --output=./test.pdf "William Sterling Blattman (1914-1989)"

It appears that the var substitution gets lost then the pdf gets rendered.  Any ideas on how to get around this?