Negotiation unavailable

Hello, im now lvl 10, i’ve been inactive for past few months, last season i got back to the game at the half of season, and reactivate my team, and i was 7th, so i went lvl up. Im always buying players from my friends who are lvl or two ahead of me, so i buy their low players its high lvl for me. Now i have tried to buy some players from my friends over negotiation and offer button is unvailable! I can still buy from nego list in transaction menu, but i want to buy players directly from my friends!! Can someone tell me what happened and what to do?? Thx