Ok, there's no knowing why something will work in some systems and not others. Given the cost of our hobby, ''you'' are lucky to be living in a time when many manufacturers and vendors are willing to let try components in our homes with the option to return them is they don't satisfy. I say that you are lucky and not ''we'' because I live in Italy and here this practice has not quite caught on. Plus due to the Euro/Dollar relationship anything that is imported from the US costs much more than it does where you are. At the time I bought my Gallo 3.5s in the US they cost $6000. Here they cost 6000 euro and a euro was worth $1.30 approx.
If I order direct from the US, it still costs me more due to high shipping costs and import duty. And shipping costs are very high now, so by the time I try a component and then send it back, it can cost me a considerable amount.
I try to avoid it, but you can do it much more easily.