If your water is too soft for shrimp and snails, there are rocks or certain types of sand that will make it harder.... and I agree that they would probably be happier in a large group of single species...
Read the reply, he said that they were not all together.
BottomFeeder dont give up! Keep trying, and eventually you will succeed. Test water daily for the first week of getting them, and maybe do water changes a bit more often.
You will get there eventually my friend