RDi 9.1.1 'Can't find class'

I'm on a pretty new install of RDI 9.1.1.

I'm working on a plug-in that extends Lpex. This Java code worked on
previous versions of RDi, and I'm even pretty sure it worked on an
earlier install of 9.1. I use the Export wizard and copy the resulting
jar file to the same directory where the iSphere plugins are located.
It's just a jar file; no folders, no features, just a jar file. I
created a User Command mapping d2free to
com.kc2hiz.lpexextensions.ConvertDToFreeAction. Starting RDi gives me a
message indicating that RDi cannot find the class.

1) In the normal Java world, I'd slap myself in the head, fix my
CLASSPATH and all would be well. But RDi has its own CLASSPATH that it
uses to find plugin jar files and I'm not sure how to tweak that.

2) Alternately, maybe there's some actual issue with the code; it's
being loaded, encountering an error and being unloaded. Is there some
way I can tell RDi to produce a detailed log of the calsses it tries to
load during startup? The expected .log file is not showing me anything.