Borussia Dortmund striker Mohamed Zidan could not return to Germany in time because he failed to issue a travel clearance from the Egyptian military administration. The 28-year-old planned to get back to Dortmund last Friday in order to continue his rehabilitation program but the unfinished paperwork obliged him to stay put. Zidan had sustained a serious cruciate ligament injury in Dortmund's 1-1 draw with Hoffenheim in April. He underwent surgery and faced a six-month layoff later on. The former Werder Bremen man was committed to his rehab at Signal Iduna Park but he cannot return to Germany in the next six weeks. Dortmund's general manager Michael Zorc was clearly upset by the news that Zidan is unable to leave his homeland Egypt. "I did not even want to believe," he was quoted as saying by Bild. "The situation is actually very difficult. Nevertheless, I hope that by the end of August Mo will find a solution and join us again." A travel clearance usually does not take much time to be issued but it's understood that Zidan has problems related to his compulsory military service.