Different Systems, different sensitivities?

My Dynamis had lain untouched since I retired earlier this year until my DCC friend (who had made sure it was one of my retirement gifts) finally forced me to bite the bullet and buy sone decoders for my proposed layout. He would help by programming the decoders using his computer and up to date Lenz system then bring the first loco across to my house to operate on my test set-up using the Dynamis. It had worked very well on his test circuit but once on mine, with the Dytnamis - not a flicker. We attached the connections direct to the solder points inside the motorised temnder and the wheels span so we thought it must be dirt on the pick-ups. Why then had it worked on the Lenz system and not on mine? Maybe there was a short somewhere. After a hour of tearing our collective hair out he reurned home to check it again, taking my Dynamis with him.

Today he returned to say he had put the loco back on his syetem and it had worked perfectly but when he had clipped the Dynamis on to the test track - nothing. He then got out his old early Lenz system and fired that up and found the loco worked but not so well as on his up top date Lenz. So when the instruction manual tells you it is possible to place any locomotive which is already DCC on your layout and it will work is that the case? What is the problem here? Could it be dirt - the latest Lenz is able to cope with a weker signal coming down the track that the Dynamis signal cant?

Stop Press. I've now practically dismantled the damn thing as gone over everything with a glass fibre brush and, yes, it works but are the different systems really so differently sensitive?