The club have been in negotiating with him but have been unable to make progress on a deal.

英訳に間違いが有れば正してください。

クラブは彼と交渉中だが、交渉の進捗はない。
The club have been in negotiating with him but have been unable to make progress on a deal.

ヒント
交渉中

答え negotiatingをnegotiationsにする

The club have been in negotiations with him but have been unable to make progress on a deal.

be in negotiations with~
~と交渉する