I'm probably doing something wrong, but when I put the clothes in the 2gal.ziplock bag & roll, I still don't get much extra room in my luggage. I'm taking the air out as I roll, but I still don't see much diff. in rolling the clothes w/o the bag. What am I dong wrong? I'm doing this with my 8yr.'s clothes, maybe its better to do with a toddlers clothes???