can someone please explain why I'm having trouble making good trades

I am Altarian, playing a post planet-rush game now, with research in the game set to very slow. I cannot make anything close to an honest deal EVER period with either the stronger or the weaker opponents. All opponents set to INTELLIGENT.

Example: The Arcaeans, who I have an "INCREDIBLE" diplomacy advantage over, are more powerful than me, but not mightily so, wanted in return for Advanced Hulls:

Adv Trade, Basic Min, Laser III, Radioative Colonization, Starbase Fort II, Superior Deflectors, and Alliances.

Now I understand some techs are more valuable to certain races, but I am getting a similar issue with the other races too (many of whom I am more diplomicatally astute). I haven't had this issue with other games - is it b/c the research is VERY SLOW? This is my first game like that. THANKS!