Hopeful students check for their results at Kasetsart University yesterday.

As soon as he found out his O-Net exam score had mysteriously vanished when the results were announced for the third time, Suparerk Tha-upparong dashed to Bangkok from Chiang Rai to ensure his chances of entering university do not disappear as well.

"There's no complaint form to fill in on the website, so I had to rush to Bangkok to file one," Suparerk explained at the office of the National Institute of Education Testing Service (NIETS). He was baffled that the score of 61 he received when the exam results were announced the first and second times had turned into a zero when they were announced the third time.

The results of the Ordinary National Educational Test (O-Net) and Advanced National Educational Test (A-Net) are vital this year because they are the main criteria for university admission.

More than 300,000 students sat the tests.

Last month, the NIETS twice voided the O-Net and A-Net scores it had announced because they were full of errors. Subsequently, the Higher Education Commission stepped in to fix the situation and the scores were re-tabulated and announced again last Sunday.

Errors remained widespread, however, and the number of complaints is growing.

Wichada Daengkulwanich, who recently finished her studies at Triam Udom Suksa School in Bangkok, said her score in Science A-Net had dropped by two points when it was announced last Sunday. Her chance of entering her university of choice had dropped significantly as a result, she said.

"My friends are also facing a similar situation. This puts us under great stress. We feel the need to consult psychiatrists now, we can't sleep and our families are feeling the stress too," Wichada said.

The stress was making some of her male friends consider entering the monkhood, she said.

Vilasinee Pattanathong from Ranong said she had twice complained to the testing service about the zero score she had received on the Science A-Net. NIETS staff assured her they had located her answer sheet and her real score would definitely be announced last Sunday.

"I got zero again," Vilasinee said at the NIETS office yesterday, where the exasperated student went to complain for a third time.

Staff later explained they had indeed found Vilasinee's answer sheet and scanned it into the server but for some reason it had not been forwarded to the Higher Education Commission.

Kriangkrai Veera-amornkul, from Nakhon Pathom, filed his complaint with NIETS acting director Prateep Chankong. "I am complaining because my future is at stake," he said. "I am not a guinea pig for adults to try this and that on."

The university entrance examination system was changed this year into one that uses a combination of O-Net and A-Net scores as well as grades from the senior years of secondary education.