Schooling fish not schooling

Question
Hi there. Whenever I buy a school of schooling fish (anywhere from 6-10 at a time), I introduce them to the tank and THEY DON'T SCHOOL! It doesn't matter how long I have them. For a year I had a school of ten neons that never grouped together, but would usually stay in pairs or trios. They hardly ever went to the top of the tank, so feeding was a hastle (if the food fell too close to the gravel they'd just stop going after it).

Why is this so? I've heard such good things from schooling species, but to me it seems they don't display their full potential to me. (20 gallon long tank, ph 6.5, usually the schooling fish are the only ones in there, dark substrate, tons of assorted plants on the back/sides, no ammonia, nitrites, or nitrates)

Answer
Dear Alex,

  One trick to getting them to school is to keep them in odd number groups.  7, 9, 11.  Also, introduce a fish that they are kind of scared of.  Something like a Krib.  He will scare them but won't mess with them.  They aren't schooling because they know nothing in the tank will bother them.