The midfielder had agreed to join the Serie A side, despite late interest from AC Milan, but he may have to stay at Craven Cottage after he was let down by an internet connection.
The Italian transfer window closed at 7pm CET on Thursday but it appears his international clearance had not arrived in time.
Kasami's agent Mino Railoa told Sky Italia: "It's ridiculous that the internet connection has not been working correctly.
"We completed all the documents before the deadline but we don't know if they arrived in time".
The decision over whether to allow the deal to go through now rests with the Italian authorities.