Dark Knight Direct Hit

[Megguido]

To add, I believe you have to get over a certain threshold (201 DH?) to start actually landing DH attacks or that the chance under this is just so low that you may not see one even in a 30 min parse.

Base DH at lvl 70 is 364. At this value, you have exactly 0% DHit chance.
So OP won't be able to land a single DHit without DH melds.