My Cherries?!?!?!

Last fall I planted 2 cherry trees-one sweet and one sour. They are little trees, my dad called them twigs, but this spring they were awash in blossoms. Hmm. I may get a bunch of cherries my first year. Yea. Sure enough I saw lots of cherries growing. When I looked a few days ago, there weren't as many cherries-but the sweet had about 5-10 and the sour had a couple. They looked close to being ripe-but not quite. This morning, after my walk with Sam, I led him to the cherry trees-only to find...NO CHERRIES! I looked again and found 2 shriveled ones on the sweet and 2 that look OK on the sour. What happened?!?! I guess I'll be buying cherries again this year. Sigh.