Disk structure error reported in Onyx but not fixable via the Disk Utility in Recovery Mode
Disk Utility will not fix every conceivable disk corruption issue. For that you need third-party apps. I use Diskwarrior and have also had success with Drive Genius.

However there is one way to do this without buying a disk repair utility. Back up your hard drive, partition/reformat it, reinstall the OS and restore your backup. Yeah it's more complicated and a bit of a PITA but will save you money.