Have Verizon's 800# double check that your SIM card is a "secure" sim card. The first sim I received with my phone did not support tap to pay, and they sent a free replacement secure sim
it sounds dumb, but try holding the phone in another direction above the reader. at the local gas station, my phone only works in certain directions.
some tag readers are very slow, probably on purpose... try holding the phone over the reader for several seconds
oh, something else, if you have a case on your phone, remove it. the NFC signal is very very weak on purpose, sometimes the case can interfere