whoa, 1.5 lbs of candi sugar would be a lot to prime with, waaaay to much. Definitely should have put it in the boil but the beer should still be ok without it. Go ahead and post the recipe, curious to take a look at it.
I guessing the recipe meant to put the 1.5 lbs of candi sugar in the boil and then prime with an extra amount of candi sugar as opposed to dextrose. I have never heard of priming with candi sugar but I would imagine it is fairly close to the same amount as dextrose.
"Whoever makes a poor beer shall be transferred to the dung-hill"
-Edict, City of Danzig, 11th Century