Vampiric Touch bugged?

So I noticed in groups with shamans when their have their mana totems down that my scrolling combat text reflects the mana regeneration. However, when I am using VT and casting damage nothing shows. So I tested it and actually watched my mana amount after a VT >> mind blast crit and I didn't receive any of the mana back nor did anyone else in my party. Anyone else wanna try and see if it works? Or am I crazy?