@S2ciMuaz
Hi there,
The reason for that is that you have a lot of higher rated players in your squad. I have checked your team and that of some other managers in your league and you all have a lot of players that are 90+ rated. It won't be easy to sell those players quickly. The more expensive the player get, the more difficult it will be to sell that player.
However, players are getting sold in your league, so there is no issue with the transfer engine. For example: yourself and Real Madrid sold a player today. Liverpool also sold a number of players both today and yesterday.
You could try to lower the price you are selling your players for or you can buy some cheaper players if you have the funds and sell those in the meantime.
