So the first thing to check is is your overall init REALLY higher than your opponent?
The easiest way to find this out, without having to add all the number, is fight the person in a 1v1 and observe who makes the start-of-battle actions first. The person who does it SECOND have the HIGHER init (this is made this way for the purpose of passive barrier. however, the order remains true even without the passive barrier and thus can be used for this check even if you don't have such ninjas)
After that, I assume your initiator is a prompt skill user you placed into slot 1. If so... well, I have no idea then.
Of course, this only helps if your opponent is from the same server as you. If not... well... where are you getting the "overall initiative is higher" bit from anyway? Granted, the same start-of-battle bit can be used to tell, but that SHOULD be consistent with the arena battle itself which should not be causing any confusions.