[plt-scheme] plt web server question

I ran the servlet w/ Instaweb (code below) and observe the following behaviour:

There is a textarea with the following text:

  Welcome to MzScheme web interface

followed by the entire text of the HTML document.

Below this textarea is another text area.  I enter

  (+ 1 1)

and press Send.  I get an empty Javascript alert and nothing else.  I
noticed that is the first textarea additional text is appended:

  send succed

That's it.

N.

#lang scheme/base

(require (planet schematics/instaweb/instaweb))

(instaweb #:servlet-path "repl.ss")