Okay, in that case it looks like the first index was not created with date math, rollover will only perpetuate the date math in the name if the initial index was created with date math (it would be named something like <index-{now/d}-000001> if it were created with date math.
In order to migrate it, it depends on what version of ES you're running, what version are you using? (Alternatively, if you're just testing, you can start over, but I understand that's not feasible with live data)