[plt-scheme] load-extension and modules

I've been working on a functional SQL for mzscheme using an extension 
for postgres built with SWIG. The extention works fine at top level but 
when I stick it into a module mzscheme bitches about unbound variables:

(module dbconnect mzscheme

   (load-extension "postgres.so")

   (define *conn* #f)

   (define (connect connect-str)
     (set! *conn* (PQconnectdb connect-str)))

   ...)

expand: umbound variable in module in: pqconnectdb


Outside of a module declaration everything's peachy. What am I missing 
here? (mzscheme 202, linux)