Update: The new target launch date is May 7.
Space Exploration Technologies will need about another week to prepare for its trial run to the International Space Station, company founder Elon Musk wrote in a Twitter post Monday.
"Am pushing launch back approximately a week to do more testing on Dragon docking code. New date pending coordination with NASA," Musk wrote.
Last week, NASA cleared SpaceX for launch on April 30, pending a final review of its flight software.
SpaceX is one of two companies NASA hired to fly cargo to the space station following the retirement of the space shuttles last year.
The company's Falcon 9 rocket has made two successful flights. During its last mission, in December 2010, it carried a Dragon capsule into orbit for a demonstration run.
For the upcoming flight, a Dragon capsule is expected to approach the space station for a series of tests to show that it can reliably maneuver and communicate in orbit. If all that goes well, NASA will clear Dragon to be berthed at the space station.
"There's no space station on the ground, so our work to date has been done by simulation and by approximating the circumstances that it will find in orbit and approaching the space station. This is pretty tricky," Musk told reporters during a press conference last week.
A new launch date is expected to be announced later this week.
Image: Artist's rendering of the Dragon capsule docking with the International Space Station. Credit: NASA/SpaceX.