I have never had any trouble, but I have heard you should open the bag and put it on the floor and let the puppy play in it and around it to get it used to the bag.
I have found that if the bag isn't big enough it's not comfortable for mine. I put a blanket on the bottom, try to make it comfortable. Make sure there is plenty of ventilation and just remember that some bags get hot in there really fast. I worry so much about my babies being comfortable in a bag... i need to find the right one. Try doing fast little trips in the bad... Walk around the house for 2 minutes then 3 then 4 to get them used to it.
I might try to make one. (Who knows how THAT will turn out!!!)
