Hull manager Phil Brown says there has been a hitch in his bid to sign Marlon King.
The newly-promoted Tigers have agreed terms with Wigan for the Jamaica international striker.
However, Brown has confirmed there is an issue between Wigan and King which means they cannot continue talks at present.
"I spoke with Marlon with Steve Bruce's permission and the two clubs have agreed terms," he told Sky Sports News.
"But with Marlon there is a problem at the Wigan end so until that is cleared we cannot get the green light to sort out the medical and stuff like that."
Brown is still hopeful he will sign three or four more players this summer.
"It is taking its time because sometimes the ball is not in our court," he continued.
"But in the main the chairman is playing ball and every club we are talking to tends to bat the ball back - but we are waiting for the green light for three or four players and once we get that hopefully we can move on."