Are you tryinging to set the hook with the rod lizard, ie jerking back on the rod when the fish bites trout style? I find that it is very hard to set the hook this way on anything other than trout due to the fact that the tip of a flyrod does not have much hook setting power.
What I normally do is point the rod tip along the flyline, make sure there is no slack in the line and when you feel a fish hit, instead of leaning back on the rod, take a short sharp strip on the flyline, normally no more than 10 inches is needed. Most saltwater fish have harder mouths than trout, and we are dealing with bigger hooks.
I find that making sure your hook point is sharp and and either slightly squashing or filing down the barb on the hook helps in setting the hook also.
Good luck, hope you catch him!