I went through something like this a few years ago. It turned out I was not pushing the stem far enough into the pump and it would get on just enough to let all the air out. Shove it on there firmly and then try it.
"My predominant feeling is one of gratitude. I have loved and been loved;I have been given much and I have given something in return...Above all, I have been a sentient being, a thinking animal, on this beautiful planet, and that in itself has been an enormous privilege and an adventure." O. Sacks