First, check again if you have the correct weapon/armor set to EQUAP.
If the ID of my Venomous Snake weapon is 24, and Snake Bite's skill ID is 13, then I need to have the script code like this in the EQ Database:
if weapon
case id
when 24 # weapon ID
skill_ids.push(13) # EQUAP skill ID
Make sure the game is saved too. There's times I just click OK on the script editor, go into Test Battle, and confuse myself seeing that there's no effect there.
Also, try testing in game too. Just make a dummy event that gives you the Venomous Snake, get the player to equip it, then make another dummy event that launches a battle encounter.
I guess what I'm saying is, just double check your work and try other methods of testing. xD