404 Error when sending Servlet request to IIS Dispatcher

I am configuring dispatcher in IIS. The dispatcher works fine for all pages but servlet.

I can send request to myServlet through CQ original url successfully (http://localhost:4503/myServlet). However when I browse myServlet through IIS (http://192.168.0.1/myServlet), 404 error occurs.

Following is more info:

CQ version: 5.5

Dispatcher version: 4.1.3

IIS version: 7.5

message in dispatcher log:

Dispatcher initializing (build 4.1.3)

farms[myApp].homepage = /content/myApp.html

farms[myApp].cache.docroot = c:\inetpub\wwwroot

Dispatcher initialized (build 4.1.3)

Found farm myApp for 192.168.0.1

checking [/myServlet]

no cache due to missing extenson in uri: /myServlet

cache-action for [/myServlet]: NONE

Filter rejects GET /myServlet HTTP/1.0

Can anyone help? Thanks in advance.