Hm, I've been staring at this issue for long enough, and searched the i-net too, but there seems to be some issue between the Excel Object model and external scripting that's just to tricky to solve in an easy way.
As claimed before: "It works on my machine" (W7 x64, Office 2007 with all updates applied, macro's and VBA enabled to the max)
Guess it's time to start on my earlier claim:
Remove the requirement of having Excel installed locally (involves rewriting in Java...)
Not sure it fits the NANY rules (I'll check that later), but I hope to continue with a tool that has the same functionality, with 1 difference, that it Just Works
I'll start to work on it asap, and pledge for NANY2012
if that applies, or re-release as version 2 (the current one really should have gotten v1.0)
That will ofcourse replace the 'Excel-installed' requirement for the 'Java-installed' requirement.