NK Maribor's Petar Stojanovic was expected to be in Hannover on Monday for a medical and to finalise the details of his move to the Lower Saxony club, but neither could come to a final agreement.
The 19-year-old Slovenian was Hannover's main target this January, with Tayfun Korkut's side keen to bolster options at right-back.
He would have challenged Hiroki Sakai for that spot, who is the only recognised right-sided defender at the club.
Stojanovic, who appeared in five of Maribor's six Champions League games this year, was expected to sign a four-and-a-half year deal.
Hannover would have paid between €1.5million and €2million for his services, with Maribor expected to work in a clause to secure a percentage of Stojanovic's transfer fee.
Last year the youngster made his debut for the Slovenian national team, coming on as a substitute against Columbia.
Steady performances in Europe's elite competition have done him the world of good, also featuring against Schalke 04.
Sporting director Dirk Dufner said the two parties ‘couldn’t conclusively agree’, before adding: “It's unfortunate because we were absolutely convinced of Petar Stojanovic in a sporting sense."
Quotes via kicker.