There is no need to use Perchloric Acid as a catalyst. Just do it like I said and it will work. 1-1.1 eq. NBS (DBDMH works better sometimes) in MeCN, stir at R.T. for 12 hours. Partition between DCM and water, and a couple successive water washes to remove the succinimide.
I don't have my references handy right now, but I can assure you that this precedure works.
Note: Make sure to recrystallize the NBS from boiling water immediatly before use. When you get your NBS, it will be a yellow powder that smells of bromine. After recrystallization, you will get glistening white plates. Dry these, weigh, and add to reaction.