I have carried on with no problems.
Did you store it under the seat in front of you, or get it in the overhead? How full was the bag?
It was placed in the overhead. If there are issues placing it wheels first (I did not have any problems) place it handle first. The bins on most aircraft are tapered making it sometime difficult to put them in wheels first. Many people do not consider putting them handle first. I am sure I stuffed everything but the fins in (BCD, reg, camera, etc.) When I get where I am going, to the boat for example, I put the fins on top of everything and zip around them using the double zippers.