Well, this is odd. In the CS it has the enchantment that you mention. In the game however, it has the weaker enchantment that I mentioned (1-4p), which combined with your Spells plugin has a spell cost of 0.25, so at least something adds up.
...
TESPCD returns no conflicts among my active plugins.
This sounds like a job for Wrye Mash.
Two One things of notice:
1) The "viper_enu" enchantment is set to auto-calculated in the CS. Is this correct? (I've never really understood what exactly auto-calculation is.)
Autocalculation takes the base cost of the enchantment itself and then calculates the enchant capacity so that you will always get the same number of uses out of them (default is five). The problem shows up when the casting cost of the enchantment is zero: five times zero is still zero.
Pretty much everything in the game by default is auto-calculated except for the stuff that was way too powerful, so the devs compensated by only giving you, like, two uses (the Vampiric Ring, for example). In my mod, everything is auto-calced.