Nothing wrong with it, you just recreated what i made, delay between when the cast of charged burst ends and when the frag does dmg, watch your gcd, the frag should trigger the absolute instant you are done casting, not .5 sec or more later. If you are fine with that, thats fine, this thread is about the people who find stuff like this a major problem.
I also want to note the frag does do dmg the instant is triggered and not when it actually hits, which is a good thing but that isn't the problem, for me at least.
Edit: after watching this slowly, i have to admit this is pretty damn close.