This paper gives a criterion for the non-vanishing of the Dirac cohomology of LS(Z), where LS(•) is the cohomological induction functor, while the inducing module Z is irreducible, unitarizable, and in the good range. As an application, we give a formula counting the number of strings in the Dirac series. Using this formula, we classify all the irreducible unitary representations of E 6(2) with non-zero Dirac cohomology. Our calculation continues to support Conjecture 5.7' of Salamanca-Riba and Vogan [19].