I can't seem to trade from Sapphire to Leaf Green, and I did all the things..

Does your Leaf Green file have a national pokedex? If not, that could be the problem.

Did you recover and give the Ruby and Sapphire to Celio on Leaf Green?

I'm having the same problem, except I can't trade over my Deoxys.

But you know, there are some items in FireRed and LeafGreen, called the Ruby and the Sapphire. you have to aquire them and get them functioning into the supernetwork machine thingie Bill has set up. THEN you can trade over.

You need to have the ruby and saphire on leaf green you get the ruby on mount embre by the team rocket guys they will give you the first password to the rocket warehouse and the saphire in dotted hole use cut on the door a scientist will take it he will tell you the second password go to team rockets base and find the scientist hope I helped!!!!!

In your Leaf Green, you must have given the R/S plates to Celio on Island 1.

You need to use a cable link to connect.

Remember, at first, to trade with R/S, you must trade in Island 1 in your Leaf Green.

You have to trade on island ONE.

You can't trade in leaf green and fire red to sapphire and ruby without getting sapphire and ruby(stones not the game) to celio.

You have to finish the elite four and the champion first.

When you go to the cinnabar gym, bill will take you to the 1,2,3 islands.

You will find celio in the first island.

You will have to give him the sapphire from Mt.Ember and ruby from the dotted hole.

Then he will establish the connection to the hoenn regions.

You need to give the ruby and sapphire to celio...

You have to beat team rocket on the Selvii islands and got to have gotten the ruby and sapphire key items in leaf green.

In LeafGreen, get the Ruby and the Sapphire. You should be able to figure out where to put the gemstones once you get them.

well first in leaf green you need to do pokemon leauge and then in the islands look for the ruby shaphire and emereld and thats what makes ya able