To compress sound files we apply FFMpeg compression. Which means if you hit an error, it's likely due to our tool not being able to compress the sound correctly.
Low / Medium
You could potentially be trying to use an audio format that Isn't supported by luna/FFMpeg compression at which point you could try to change its format in an audio application.
If thats not the problem, then it could be down to the FFMpeg tool not being able to process the sound correctly resulting in an error, a way around this would be to compress the sound manually.
If neither of the previous steps helped, please have a read of our Common Issue page on Audio for further troubleshooting steps.