My description of rolling stock was a shorthand way of describing my  situation without getting too wordy.  Believe me, I have manipulated the cars over the magnet in many ways.  I hadn't thought about coupler  height, however.  I will check this suggestion out.  All my couplers are kadee #5.

Forgive me  if this is not the place to discuss this topic: but I recently purchased 8 E-Z Mate Magnets with Brakeman and was perplexed when they had no effect on the rolling stock when the train passed over them.  I followed the instruction on the package to a "t"( that's an old vernacular phrase). I have cork roadbed and regular track, but package indicates that this combination  will work.  Any thoughts?