[plt-scheme] Difference between DrScheme and MrEd

I have a program that runs fine in MrEd, but in DrScheme I get the
following cryptic error:

  module: identifier already provided (as a different binding) in: for/vector

for/vector is a comprehension I have implemented that is required by a
few dependencies of the module in question. These dependencies all
compile and run fine (in MzScheme). My guess this has something to do
with DrScheme's compilation process. Any ideas on how I can convince
the good Dr to load my code? Perhaps I can flush its cache of compiled
files, for example?

N.