I can't stop thinking about four sad kids from Cameroon and how our country broke their hearts.

Last weekend, the Cameroonians — two boys and two girls, ages 14 and 15 — were to arrive in Philly for two weeks of fun hosted by Philadelphia Youth Basketball.

PYB creates programs aimed at helping young people, mostly from low-income communities, develop their potential as students, athletes, and leaders.

Last year, PYB sent some teens and staffers to rural Jamaica, where they helped run a basketball clinic.

The trip was a slam dunk. The Americans and Jamaicans parted as dear friends – and with an enthusiastic new interest in cultures, languages, and people beyond their own borders.

This is citizen diplomacy at its best. It unfolds through simple interactions that demystify differences and create appreciation and connection. What a beautiful thing for children to experience.

This summer, PYB wanted a similar international experience to unfold here. Through a volunteer, PYB president and CEO Kenny Holdsman connected with Jeanne Tchuinga, director of the Chanterelles Bilingual Secular Middle School — a tuition-free school for low-income children in Yaounde, Cameroon's capital city.

To Philadelphians, Yaounde is probably mostly known as the home town of 76ers star center Joel Embiid.

"He's a role model in Cameroon," Tchuinga told me via email. "Everyone has proudly followed his career."

After crunching numbers, PYB decided to spend $13,050 on a trip of a lifetime for four of Tchuinga's students and two adult chaperones, who would lodge for free with Philly host families.

During the day, they'd play basketball with the boys and girls of PYB. Nights and weekends, they'd squeeze in visits  to Washington and New York, moonlight movies in Mount Airy, miniature golf at Franklin Square, and dinner among the swinging hammocks of Spruce Street Harbor Park.

And, maybe, a few minutes with Embiid himself, whose business manager had gotten wind of the visit and was looking into a possible meet-and-greet.

The Cameroonian kids, who have never been outside their country, were dizzy with excitement as word of their good fortune pinballed around their hilly neighborhood.

The only people more ecstatic than the kids were their parents, Tchuinga said.

"They are poor," she said of the families, who work multiple low-income jobs. One mom sells prepared food on a street corner; another sells sweets at a school playground. One dad leads photography tours in the city; another does bookkeeping.

"They cannot afford two weeks of vacation for their children. They had to make enormous sacrifices even to afford their children's passports. But they were so excited! They knew this was a unique opportunity."

And then America sucker-punched them all.

When the Cameroonians applied at the U.S. Embassy in Yaounde for nonimmigrant-visitor visas, they were turned down under something called Section 214(b) of the Immigration and Nationality Act.

All applicants are subject to the section, which presumes that they intend on becoming immigrants here. It falls on them to prove otherwise during the petition process. Consul officers look for evidence of applicants' strong ties to their countries of origin that, presumably, they'd be loath to sever by going AWOL in the States.

We're talking about things like family bonds, owned property, established careers, strong social connections to the community and local economy. In reviewing the Cameroonians' applications, the consul determined that the students were not able to meet the requirements of Section 214(b).

That's because they're kids. They don't yet have careers, own property, or enjoy social and economic influence in their community.

What they do have are strong families they cherish. PYB's Holdsman can't believe this point was lost on consul officers.

"Do they really think the kids would want to live with us?" he asks, incredulous. "My wife and I just became empty nesters. Trust me, it is not our intent to fill our house with 14-year-olds who have families back in Cameroon."

Despite intervention from staffers of U.S. Rep. Dwight Evans on behalf of PYB's mission, the trip remained a wash. Which doesn't surprise Harrisburg immigration attorney Craig Shagin. America's new zero-tolerance immigration policy, he says, is more akin to a "100 percent-intolerance" policy.

"Applicants have to supply more information than ever before, and it's still not enough," he says.

Case in point:

For 33 years, Germantown Friends School (GFS) has run an annual student-exchange program for participating ninth-grade Spanish students. They live with Mexican students' families for a few weeks' immersion in the country's language and culture. Later, the GFS families reciprocate.

This spring, for the first time ever, the Mexican kids were denied visas. Even though no Mexican student in the GFS program has ever not returned home.

"It's incredibly disappointing," says GFS parent Liza Somers, whose daughter Gemma Mines couldn't wait to reunite with Lei, her Mexican counterpart. "Lei's family was so welcoming and generous. We're so embarrassed."

Although a few weeks have passed since the U.S. denied entrance to the Cameroonian kids, they remain devastated.

"They are almost inconsolable," says Tchuinga of the students, who are being mocked by children who'd been jealous of the upcoming trip.

"I feel helpless and ridiculous in the eyes of parents, who did not seek out a trip for their children," she says. "I have disturbed these families for nothing."

No she hasn't. America has.

Want to let the Cameroonian families know you care? Write a note of support and email it to me at polaner@phillynews.com, and I will forward it to them, in the name of citizen diplomacy. Thanks.