[racket] Error trying to use "Snooze: Object Relational Mapping of PLT Structures"

Dears,

I want to write a little web server using PostgreSQL as database. I found an OR-mapping library on PLaneT which is called "Snooze". I follow its doc on:

http://planet.racket-lang.org/package-source/untyped/snooze.plt/2/9/planet-docs/snooze/quick.html#(part._.Start_using_.Snooze)

and write below code:

#lang scheme/base

(require (planet untyped/snooze:2)
         (planet untyped/snooze:2/postgresql8/postgresql8))

(define-snooze-interface
  (make-snooze (make-database
               #:server "localhost"
               #:port 5432
               #:database "testdb"
               #:username "test"
               #:password "te5t"
               #:ssl 'no)))
         
(provide (all-from-out (planet untyped/snooze:2))
         (snooze-interface-out))

Then I click the "Check Syntax" button inDrRacket, after a while it pops error below:

. ../../../Library/Racket/planet/300/5.2.1/cache/cce/scheme.plt/6/3/contract.ss:319:30: expand: unbound identifier in module in: proj-get

I found the file "contract.ss" but I really do not know how to correct this.
Could someone help me?