SkStuff item data issue - 1.8.8

[yLeoft_]

So I'm creating a block extension minigame and I need the wool block to have the nbt "{CanPlaceOn:["wool"]}"
But it is giving this error:
':["wool"]}"' is not a valid item data (blockex.sk, line 37: give player 64 white wool with custom nbt "{CanPlaceOn:["wool"]}")

My code:
command /testbex:

permission: op
trigger:

give player 64 white wool with custom nbt "{CanPlaceOn:["wool"]}"​