In my particular the world El Dorado county ca, it really doesn't matter, however if everyone chasing turkeys is using a crow call that might be part of the problem you are having, they have have been over exposed to that technique, a coyote howl a owl hoot they will all work, I even used a duck and goose call successfully, I pretty much get away with a gobble or yelp, being more aggressive being less aggressive both work under different circumstances, where I'm successful this year I may not be next year, and I have figured out why over 35 years after my first turkey hunt, whats you're approach are you trying to call down out of the roost, trying to call them once they hit the ground, sometimes time of day will greatly improve you changes, I spent almost 2 seasons and on what I'm pretty sure was the same tom, he wasn't the heaviest tom I've taken at 17 lbs they usually loose some weight as the season progress's but he was the largest and from the almost Jurassic look to him he was the oldest, our season generally runs last Saturday in march to the first Sunday in May, Hunted him 2 to 3 time a week for most of 2 seasons, I was finally successful when I approached his roost at around 11 AM, some days I spent hours having him strut around just out of range or never getting clear of cover, twice I shot the wrong bird, finally with a near end of season late morning approach he ran into the end of my barrel perhaps with no more than 10 or 15 minutes of calling, that approach works well when a tom has a large flock of hens to keep him busy, remember the hen is supposed to go to him, we are reversing that senairio, if he hits the ground with a handful of hens its very difficult to call him away from that first thing in the morning, so a later approach may help improve the odds.
