Schools' hopes of a "quick fix" to climbing the league tables were dashed this week when results of a new computing course emerged.
Schools which introduced the DiDA course worth four GCSEs are scaling down their commitment to it after staff concerns over unofficial initial results.
The qualification was billed as a replacement for the general national vocational qualification in ICT, which had been criticised as a "soft option".
Staff have revealed it is impossible to get good grades in the qualification without devoting more time to it than to the GNVQ. Many gave the same amount of teaching time to the GNVQ as for maths GCSE.
Around 900 secondaries have signed up for Edexcel's DiDA course. By September it will be possible to study it in four-GCSE, two-GCSE and one-GCSE versions.
Before the results emerged, Paul Hynes, the lead adviser on ICT to the Specialist Schools and Academies Trust, told an internet discussion site that DiDA showed up the GNVQ, which will be phased out next year.
He said: "The GNVQ ICT is a devalued commodity. It has been responsible for ICT departments being turned into a 'curriculum fix'. The quick fix has gone."
Around 120,000 pupils have signed up for DiDA. Most teachers say the new qualification - one of the most innovative courses available - has captured teenage imaginations. It replaces paper exams and coursework assignments with electronic portfolios of project work with spreadsheets, graphics and PowerPoint.
The pilot group of 45 schools which started DiDA in 2004 have now received results from the first module of the course.
In an internet discussion group an advanced skills teacher caused concern by revealing results at his secondary fell from a 95 per cent pass rate in GNVQ in 2005 to 27 per cent on the first DiDA module.
He said he had advised 85 schools on implementing DiDA. They were all cutting back, either from a four-GCSE commitment to two, or two to one. The AST said schools were realising that to get good results they would need to devote far more than the GNVQ's three hours a week.
An Edexcel spokeswoman said a few schools and colleges had underperformed on the first module but some produced "superb work". Some had registered pass rates of 85 per cent or more.
To offer the four-GCSE version schools needed to be imaginative, she said.
It should be used to support other subjects, such as design and technology and music.
She said: "For this to be a meaningful qualification, it cannot be seen (by schools) as a GNVQ mark two."