Boeing suffered another disappointment, as the company was forced to delay its Starliner launch, sending it back to the factory to resolve an issue.

As private companies race to provide NASA services, as well as capitalize on the commercialization of space, Boeing has been developing a reusable capsule to ferry crew back and forth to the International Space Station (ISS). Unfortunately, Boeing’s project has been plagued with issues and delays.

The latest issue involved four propulsion system valves that were not operating correctly, forcing the latest test to be scrubbed. Even afterward, the valves stayed closed.

“Mission success in human spaceflight depends on thousands of factors coming together at the right time,” said John Vollmer, vice president and program manager, Boeing’s Commercial Crew Program. “We’ll continue to work the issue from the Starliner factory and have decided to stand down for this launch window to make way for other national priority missions.”