The 18 year old, Michelle Wie, is one of the youngest and greatest female golfers in the game. But this past Saturday at the State Farm Classic, she cost herself thousands by making one fatal mistake. She forgot to sign her scorecard!

Wie sat red-eyed in front of reporters and photographers trying to explain the mistake. She says on Friday after her round by the 9th green tent where players go to sign their scorecards, she was chased down by volunteers who pointed out that she hadn’t signed. Although she returned to the tent and signed the scorecard, the volunteers say because she previously walked outside of the roped tent area with the scorecard unsigned, it was too late and the mistake was final. To add more insult to injury, it wasn’t until Saturday morning that the volunteers told Wie and the officials of the mistake…after she’d played her final round of golf.

Wie said she usually signs her scorecard immediately, and had no idea why she didn’t Friday. “Hopefully it won’t happen again,” she said.

The signature rule is at the heart of golf’s honor system. Golfers are held accountable to maintaining thier scorecards and making sure that officials attest the scorecard.

Wie’s disqualification resulted in her loss of possibly winning the top prize of $255,000.