Although negotiation is available at level 4, no one will buy your 3* player because the level 2 managers who see him as 5* don't have a negotiation list. If he is a 5*, it may work.

Also, the highest quality players are listed, to the point that if your player isn't 1sp short of the next star (with stat that adding 1sp will gain him a star), then he probably won't be listed in negotiation.

Another problem is that very, very few people actually buy players age above 27 through negotiation.

For a player like this you should try selling him in auction again and again and hope someone pick him up eventually. Aging players are more powerful by default but expansive to use, therefore very few managers want them unless they have no alternative option and in need a reliable player for that position badly.