I have the same problem, but what I have found to help
is riding a bicycle. And I'm not talking about the stationary
ones at the gym. I have a couple friends who are semi-pros
for small cycling circuits and their calves are sick.
Before my bike was stolen (bastards), I would ride roughly 10-
15 miles a day. Although, the size (girth) of calves didn't
increase that much, the improvement in definition and hardness
was well worth it. When I would flex my calves and see
veins running across them, it was definitely motivating. Since
then, whenever I do abs I do calves.
3-4 sets 35@350lbs/30@375lbs/30@375lbs/15@390lbs
[Note that these are leg press weights]