Presta valves are tricky. You might be doing something not quite right - but I've had that problem when it was far from my first time. ONe thing I learned was to move the valve so it was at about 1:00 - though I would have thought having hte tire pump thingy pointing down woudl have worked better. I can't fill the tire with the pump thingy on the bottom half. (On the other hand, a friend's tire can only be filled on that half.)
It's only a mild "rookie" thing to throw yourself at the mercy of the group for helphing you manage filling the tires. (We had a lady once say "I don't know what is wrong with this tire guage, it says my pressure is 25 psi!" on her third ride, where she'd been riding a good 15 mph on her hybrid with us... oh, yes, she *was* doing that on 25 psi!! When her tires got inflated she said, "I don't even have to pedal!" So... be new! Watch how people react... you'll be able to tell who the newbie-friendly folks are and who you'll want to ride with :-)