Attempting to properly set an "srv" record in my domain's DNS settings.

Here's some background, and what I'm trying to do:

Environment: Windows Server 2008

I'm running Alt-N's Mdaemon Mail Server.

I'm also running Apache2.2 as my web server.

Mdaemon's Webclient is listening on port 4777.

When a user goes to "mydomain.com:4777" they can log into the web mail client.

I'm trying to create a DNS "srv" record that will allow a user to type "webmail.mydomain.com" , to access the web mail client.

Here's how my srv record looks:
================================
Service: _http._tcp.webmail.mydomain.com.
Protocol: _tcp
Name: @
Priority: 0
Weight: 5
Port: 4777
Target: webmail.mydomain.com.
TTL: 1 hour


FYI... I also have a CNAME record of:
======================================
Host: webmail
Points to: mydomain.com
TTL: 1 hour



When a user types "webmail.mydomain.com", it just takes them to the main site. What am I doing wrong?