Human error caused an exam results mix-up that has reduced to a shambles the application process for mature students to nursing.
After days of confusion and distress, some applicants want to re-sit the aptitude test that determines entry to the college nursing programmes.
Almost 1,600 applicants involved were still awaiting their results after emails sent out last Friday were withdrawn because of errors.
Among the complaints from applicants were that the emails they received included an incorrect CAO number, an incorrect "qualifying score" and incorrect totals.
The Public Appointments Service (PAS), which operates the test and communicates the results, last night apologised to the candidates and said it hoped to be able to re-issue results today.
However, the Institute of Guidance Counsellors (IGC) expressed alarm at what happened and said "any incident like this undermines applicants' confidence in the process and causes unnecessary distress and hardship to them".
IGC spokesman Betty McLaughlin said "the candidates may themselves prefer to re-sit and view this situation as a shambles".
PAS spokesperson, Tommy Quinn said last night that the issue of release of the incorrect results was being thoroughly investigated.
He said the problem appeared to have been caused by a mail merge error, where the wrong fields were selected and included in the emails sent out to applicants.
"As a result incorrect 'qualifying scores' were included," he said.
Mr Quinn said human error was involved.
He said they were very conscious that this had caused great distress and upset to candidates.
"Throughout the day we have responded to individual queries from candidates and we will continue to provide this service for as long as required," he added.
He said there was no question of candidates having to re-sit tests, and at this stage in the season, it would be extremely difficult
Colleges offer a limited number of places on nursing degree programmes to mature applicants and use this test as the means of selection.