Michelle, I'm certainly no expert, but it may be as simple as adding too much water to the soil you are putting into the baggie. Try dribbling only a tiny amount over the soil and mix it in with your hands just until you can squeeze it together gently and have it stick together. Or, try the method which calls for putting your soil and cutting into a small pot and then put the pot into the baggie. That way, if you've used too much water it can drain out of the pot, you'll see it in the bottom of the bag and you can open it up, drain off the water and pop the pot back in and close it up again.

Annececilia,
Thank you for the advise.I'll give it a try.
michelle