A controversial initiative that pays high-school students for passing Advanced Placement tests has failed to spur more kids to make the grade.

Students at 25 low-income city public schools and six parochial schools were offered private money on a sliding scale – from $500 to $1,000 – if they passed their five-point AP subject tests by scoring between 3 and 5.

The new program, largely targeting black and Hispanic students, was meant to prepare more kids for college and give them a financial boost to get there.

Despite the dangle of dollars, the number of students passing their AP tests in the 31 schools actually dipped to 1,476 this year – down five from 2007, when no cash was on the table, according to data released yesterday by the Council of Urban Professionals, which distributes the money.

The passing rate fell from 35 percent in 2007 to 32 percent this year in a result that surprised even those who have been skeptical of cash-for-kids programs.

“I would have thought that the kids who were on the margins [of passing] – that you would have seen many of them go over the top,” said Dr. Pedro Noguera, a professor of teaching and learning at NYU who has questioned the long-term viability of incentive programs in schools.

“Why that didn’t happen – we should look closely at why that’s going on,” he said.

Those behind the privately funded initiative said they saw many positive results on which to build, including an 8 percent increase in the number of AP tests taken and a 19 percent increase in students scoring at the top point level.

Passing rates at nine of the 31 schools increased by more than 50 percent.

“We’re going to try and figure out what worked at these schools and how we can apply what happened at these schools to some of the other schools,” said Whitney Tilson, a co-founder of the initiative.

“Obviously, we’ll be disappointed next year and in future years if there’s no increase in the number of students passing, but we’re not discouraged at all.”

More than 1,100 students are collecting nearly $1 million for their work.

“It got to the point that we were sitting at breakfast and prepping each other on AP US history trivia,” said Jason Tejada, 16, a senior at All Hallows HS in The Bronx.

“I don’t see any downside to it,” he said of the program. “It’s pretty straight and simple: Work hard, we’ll pay you.”

yoav.gonen@nypost.com