APEX

Hi all, I'm trying to implement the tutorial here http://www.inside-oracle-apex.com/adding-captcha-to-your-oracle-apex-application/ and I'm trying to run the function he mentioned in step two:

CREATE OR REPLACE FUNCTION checkRecaptcha
  ( pPrivateKey IN VARCHAR2
  , pRemoteIP   IN VARCHAR2 := OWA_Util.get_cgi_env('REMOTE_ADDR')
  , pChallenge  IN VARCHAR2
  , pResponse   IN VARCHAR2
  )
  RETURN VARCHAR2
IS
    --
    vRequest      Utl_Http.req;
    vPostText     VARCHAR2(500);
    vResponse     Utl_Http.resp;
    vResponseText VARCHAR2(2000);
    vError        VARCHAR2(200);
BEGIN
    ----------------------------------------------------------------------------
    -- Build text for the post action.
    -- For a field description, see
    -- http://recaptcha.net/apidocs/captcha/
    ----------------------------------------------------------------------------
    vPostText :=
      'privatekey='||Utl_Url.escape(pPrivateKey, TRUE)||CHR(38)||
      'remoteip='  ||Utl_Url.escape(pRemoteIP,   TRUE)||CHR(38)||
      'challenge=' ||Utl_Url.escape(pChallenge,  TRUE)||CHR(38)||
      'response='  ||Utl_Url.escape(pResponse,   TRUE)||CHR(38)
    ;
    ----------------------------------------------------------------------------
    -- if you need to set a proxy, uncomment next line.
    ----------------------------------------------------------------------------
    /* Utl_Http.set_proxy('proxy.it.my-company.com', 'my-company.com'); */
    ----------------------------------------------------------------------------
    -- Send data to reCAPTCHA.
    ----------------------------------------------------------------------------
    vRequest := Utl_Http.begin_request
                  ( url    => 'http://api-verify.recaptcha.net/verify'
                  , method => 'POST'
                  );
    Utl_Http.set_header
      ( r     => vRequest
      , name  => 'Content-Type'
      , value => 'application/x-www-form-urlencoded'
      );
    Utl_Http.set_header
      ( r     => vRequest
      , name  => 'Content-Length'
      , value => LENGTH(vPostText)
      );
    Utl_Http.write_text
      ( r    => vRequest
      , data => vPostText
      );
    vResponse := Utl_Http.get_response(vRequest);
    IF vResponse.status_code = '200' -- the HTTP call was successful
    THEN
        Utl_Http.read_text(vResponse, vResponseText);
        -- Has the user entered a correct solution?
        IF vResponseText LIKE 'false%'
        THEN
            vError := SUBSTR(vResponseText, 7);
        END IF;
    ELSE
        vError := 'HTTP status: '||vResponse.status_code||'-'||vResponse.reason_phrase;
    END IF;
    --
    Utl_Http.end_response(vResponse);
    --
    RETURN vError;
END checkRecaptcha;

but it refuses to work. A popup box with a single button 'submit' appears. I press it and then I get this error:

Not found*
The requested URL /apex/wwv_flow.show was not found on this server


All my other functions and procedures run just fine without error. This particular one is the only one that doesn't run.

Has anyone encountered this before? How do I overcome it?

Thanks
-J