DWCS4: Cannot connecting to MySQL DB failing

Hello. I have a webpage that I'm trying to open a db connection in and it's failing.  This happens when I fill out the MySQL Connection dialog and click "Select" or "Test" after filling out the information.  The message I'm getting is:

HTTP Error Code 404 File Not Found.  Here are some possible reasons for the problem:

1) There is no testing server running on the server machine

2) The testing server specified for this site does not map to the http://ftp.(mydomain)/_mmServerScripts/MMHTTPDB.php URL.  Verify that the URL Prefix maps to the root of the site.

Now I have several sites that have connections to MySQL DBs and I have set up this particular site the same way.  I do remember having this issue before with the other sites but cannot remember what was done to make them start working.  Actually I believe that at some point they just started working without me doing anything.

Here is the information I have in my Testing server in the Site Manager:

Server model:  PHP MySQL

Access: FTP

FTP host: ftp.mydomain.net

Host directory: /public_html/

Login: root hosting account name

PW: same as above password

Use passive FTP is checked

URL prefix: http://ftp.mydomain.net

When I click "Test" in this dialog I get a successful connection confirmation.

I am able to upload files to the server normally.

I have verified the DB user I am using in the DB connection has full privileges to the database and the database name is correct.  Same stuff I do with my other sites.

Help please.

Steve