Orbital Sciences trial cargo ship Cygnus will dock with the ISS at least two days behind the original schedule due to a software glitch.
Launched last week from Virginia atop the Antares rocket, the cargo capsule was originally expected to reach the orbital outpost on Sunday.
However, a software problem was uncovered on Sunday, barely six hours before the docking was about to take place, resulting in Cygnus rejecting navigation data transmitted from the ISS.
Orbital Sciences said in a statement it had found the cause of the data discrepancy and was developing a software fix.
The next opportunity for the capsule to rendezvous and dock with the station will be on Tuesday.
Orbital Sciences is one of two firms hired by Nasa to fly cargo to the space station, a project of 15 nations, following the retirement of the US space shuttles in 2011. If the trial is successful, the company hopes to make its first paid cargo delivery, under a $1.9 billion contract with Nasa, in December.
Orbital Sciences was already preceded by its competitor SpaceX, which had become the first private operator docking its ship and delivering cargo to the ISS in 2012.