I am having an issue with one of my new Protank IIs. When I attach it to my MVP It acts like it is plugged up. I have tried the bottom on several of my tanks and changed the atty as well, it does the same thing on all my tanks. Air moves through it if I suck or blow out of it off the MVP but it just locks up or something as soon as I attach it. I am having no problems with any of the others, just that one bottom. Any ideas on how to fix it?