Heya guys
Even tho most of you explained why the negotiations couldn't be completed, let me summarize the different rules.
In order for a negotiation to be successful, there are some conditions that have to be met:
1. Both Managers have to be at least Club level 4.
2. They should be on the same server.
3. The player that is to be bought should be on 99% to attaining their next star.
If all these requirements are met, then there should be no problem in completing the negotiation.