Potential students are receiving the wrong or incomplete advice about which qualifications are available to them because the website of the National Careers Service is missing the details of thousands of courses.
Young people are particularly badly served: although the website is intended to offer information on choosing courses for pupils aged 13 and over, details of most sixth-form colleges appeared to be missing.
Test searches by TES suggested that, in some categories, less than half of courses were recorded on the website, operated by Hotcourses under contract for the government. A sample search of the directory for A-level courses in English in London, for instance, found results in only nine colleges. However, a manual check found that a further 15 colleges offered the course.
Only a handful of the 94 sixth-form colleges in England are represented on the website. With many sixth-form colleges offering 40 or more options, the missing courses would easily run into the thousands. The site search omitted all 12 of London's sixth-form colleges from its results.
Nationally, the database recorded only 44 colleges offering A levels in English, a fraction of the real total. Ironically, some courses, such as Stanmore College's English A level, appear on Hotcourses' own site, but not on the official directory.
The National Careers Service said it was providers' responsibility to submit their data for the website, which launched last month, and to ensure it was up to date. "There are some issues with the data in the course directory, and we are continuing to encourage colleges and providers to ensure that the data is complete," said Joe Billington, director of the service. "The flip side of that is that we all want to improve on that; we want to improve the search engine, its accessibility.
"There are responsibilities on both sides, but the primary issue we have at the moment is trying to improve the quality of that data."
Mr Billington said one issue that was causing many courses to disappear from the database was the need to keep updating start and end dates for courses held several times a year. "There is a responsibility on colleges and providers to make sure the data is up to date, absolutely. It's a big part of why the course directory isn't showing all of the courses that are available," he said.
Colleges acknowledged their responsibility, but said it was inevitable that a large data collection project would need someone to chase up missing entries and ensure the information was reliable and comprehensive. "Some principals weren't aware that they had to upload their data," said Joy Mercer, director of policy at the Association of Colleges.
She said colleges had reported other glitches, such as a provider in Yorkshire being listed as the top result for hospitality and catering courses in every part of the country. A-level provision was also often missing.
"If, as I did, you sit at home in Lewes and look for literacy courses and numeracy courses, you can't find any - even though I'm 10 minutes away from my nearest college," Ms Mercer said. "The biggest omission is sixth- form colleges. The assumption is that they're not included because it's a Skills Funding Agency initiative."
The perception that the National Careers Service was for adults only was fuelled by the Department for Business, Innovation and Skills (BIS) contributing pound;80 million to its running costs, while the Department for Education paid just pound;4 million.
In fact, the careers service is expected to offer advice through its website to children from the age of 13, and BIS says it will support 370,000 young people.
But it was failing to provide a central resource where students could find out their full range of options, Ms Mercer said. "With the loss of Connexions, there is a need at least for a comprehensive course directory that people in schools can refer to and that students themselves can use."
1m telephone advice sessions will be held by the National Careers Service each year.
20m online advice sessions will be held.
700,000 adults will be offered face to face advice.
370,000 young people will be advised through the helpline and website.