Can I claim HOH but not claim the child as a dependent?

I have split 50/50 legal custody with my son. Her mother and I dont live together and we switch back and forth every year who claims him as a dependent.  I have filed head of household every year and only claim him as a dependent every other year. This year is not my year to claim him as a dependent and for some reason this year I cannot get Turbo Tax to accept HOH filing status without having my son listed as a dependent. Any help?