Gregory van der Wiel's agent has revealed that the full-back has not agreed personal terms with Valencia.
Reports suggested that a January move had been finalised for the Ajax right-back but Hakim Slimani insists a transfer fee will have to be negotiated.
He told Voetbal International: "Valencia will have to reach an agreement with Ajax first.
"Valencia would be a great next step in Gregory's career.
"They really want him as their new right-back and Valencia are a big team in a superb league."
Van der Wiel, 23, has already made 25 appearances at international level for the Dutch.
