Diplomacy with the Nommo (squids)

[allan2]

I'm still playing my first game, as the Humans (the Greater Solari Empire), and I'm around turn 120, a Senate member second in votes only to the New Orions, and since almost the beginning of the game the Nommo have been extending treaty offer after treaty offer with me, which I've accepted politely, to where we are now defensive allies and my people like them a lot (casus belli is around +180, and the relations slider is comparable). However, I have not yet been able to get them to approve a single tech trade (I've been going mainly for their "soil enrichment" advance, which I figured would beef up my population further (especially out of the many "yellow" planets I'm trying to make something out of), but I've also gone for others). The Nommo are very lacking in some key military techs, so I've offered two and even three of my military techs (I WANT them to be strong, given our alliance) in exchange for just the one tech I wanted--but they always "regretfully" tell me they cannot accept. I'm wondering if I need to take some sort of firmer hand diplomatically, although would my people get unrestful?

BTW, I also have the "Official Strategy Guide" (bought it with the game), and every race described in it EXCEPT the Nommo have a section called "diplomatic tendencies" which pretty much describes what tone you need to take to get along with a particular race. With the Nommo there are no such tips. The Nommo are by far the friendliest race towards me, most others range from neutrality to war (and thus I haven't been real successful trading techs with them), and yet I can't make a deal with them. Anyone figured out a way to talk with these guys?