Why can't I trade between my FireRed and Sapphire?

Question

I'm trying to trade Eevees to Sapphire for Natdex evolutions.
On Firered, it said "I'm sorry, we can't conduct trades with trainers far away in another region yet.." while Sapphire says "Sorry, we received a transmission error".
- I have the Natdex in FireRed, and two badges in Sapphire.
- Authentic cartridges
- Brand new link cables

Comments

Did you do the task that lets you be able to trade between FireRed/LeafGreen and Ruby/Sapphire/Emerald? You need to have given the Ruby and Sapphire to Celio so he can upgrade the machine that allows you to trade between FireRed/LeafGreen and Ruby/Sapphire/Emerald

---

I did not. I'm currently working on it. I thought that requirement was only for Emerald, and National Dex for Ruby/Sapphire, lol

---

Ok lol. Yeah, doing that request is required for Fire/Red Leafgreen and Ruby/Sapphire/Emerald in addition to the other things that let you trade between the games

Answer 1

The reason you can't trade between FireRed and Sapphire is because you haven't completed the post-game quest of helping to complete Celio's Network Machine to allow trades between the two games. Once you complete the quest, you can then trade between FireRed and Sapphire, as the only requirements for Sapphire to trade with FireRed/Leafgreen is having the Pokedex and having at least two Pokemon in your party since you automatically get the National Dex after trading between FireRed.

Source