DW has a log that should tell you the exact reason for the failure. usually its the wrong username and password. The username and password is the same as your cpanel username and password.

If you have verified you can login to cpanel, but ftp still does not work, then you may be connecting to your old host.

When you ping ftp.example.com what IP address comes up? It should be the same IP address found in your welcome letter. If it is different, you probably have not completely resolved the domain name yet.

You can either change ftp.example.com to the temporary IP while you wait for the domain to resolve, or simply wait for the domain to resolve.

You can try to flush your DNS resolver cache as well to see if you can get the new IP when you ping.

To flush your DNS resolver cache in windows go to:

Start > run dialog > type in "cmd" (no quotes) then the terminal appears. Type "ipconfig /flushdns" into the terminal. (no quotes)

It should tell you you have flushed your cache.

Then try to ping ftp.example.com and see if you get the correct IP.

If that does not help, you can submit a support ticket with your login details so we can check.