Why do I have so much difficulty using the FREQUENCY formula consistently correct?

I know it is an array formula, I use control, shift, enter to enter the formula. But I so often struggle with getting it to work properly that is is often frustrating.

This formula is so central to statistical analysis, I use it often & I struggle to get it to work almost every time. What am I doing wrong and, more importantly, when it works, what am I doing correctly: if I knew that, I wouldn't ever have a problem.

I've read the Help on the MS site a million times. I need some plan English and a patient person with whom to dialogue/monologue.

Thanks,

SIL