There's very little soil in those containers and tomatoes are heavy feeders. I suspect regular fertilization is one of the keys to success. And, as Steve suggests, getting sun is crucial.
I have heard of other people with the same problem. Apparently, the container is a little small for the root system needed and container dries out too quickly
The topsy turvy didn't do well for me either. A friend of mine used a five gallon bucket and her tomatoes were huge. she just cut an X in the center of the bottom of the bucket, hung the bucket up and filled it 1/2 full of potting soil. I'm trying that this year.
Lori - same here as Debi said. My husband has tried them the past 2 years w/just so so results. Even if a light weight soil is used and not even filled to the top, it gets extremely heavy. He hung ours off shepherd's hooks and still had to anchor them w/wire to a deck post to keep them from falling over.
Think we'll go back to a large plastic tub - holes drilled in bottom for drainage.
I used that topsy turvy last year, and had about 5 cherry tomatos. (I live in a apt and have a small yard but tons of slugs) I had always used large planters in the past, and had huge plants with lots of tomatos on them until I tried that thing. This year my cherry tomatos are back in a large planter (with the tomato cage around them because they need the support) and I have a large supply of tomatos, and still lots more on the plants.
Think we'll go back to a large plastic tub - holes drilled in bottom for drainage.