Right, now you're speaking double dutch!
Dative is the indirect object (or recipient); Genitive is the possessive, Ablative is for agents / instruments or sources expressed by "by", "with" or "from". So a "dative possessive" is just not making any sense to me, it's either-or.
I was miffed by my dictionary, as I couldn't determine the correct form of "iaciam", let alone conjugate it properly (hence my lack of certainty about the "t"!). I might pick up a copy of Latin Grammar (Gildersleeve, B.L. and G. Lodge) or New Latin Grammar (Allen, Joseph Henry and J.B. Greenough) ...
Edit: ooo, a new version!