Domain Mapping not working!

Hello.

I'm running a Wordpress Multisite on this domain and I installed your Domain mapping domain.

I followed all of the steps in the Usage section. I first tried the option using my server's IP without any success. Then I found out through my Hosting Provider that it didn't work because the plugin required an independent IP address for each domain being mapped and I had a shared IP. (Is this correct?)

Later, by re-reading the Usage section I saw that there was another way to accomplish this by using the CNAME method. I tried this and it also didn't work!

Please help me with very detailed instructions as to how I can make this work, if not by a shared IP, then by CNAME.

Thank you for your support and prompt response.