My Dwarf hamster cant drink from Bottle?

I got two baby Dwarf Hamsters yesterday, I've noticed since I got them that whenever they try to drink from the water bottle that nothing comes out (Yes I did fill it with water) I poked the end with my finger and water came out fine, but it took a little bit of force. Im worried my Hamsters tounges are not strong enough to push the ball inside, So since this morning I've been watering them from a medicine dropper once every 3-5 hours. And I put lettuce in the cage since it has lots of water in it, And they've been it eating non-stop. But hat should I do? What water bottles would be easier for them to drink from? And how many times a day should I be watering them form the Medicine dropper until I get a new water bottle? The water bottle that I have in te cage is the one that comes wiht CritterTrail Double decker habitat, If that helps at all.