Answer: Chinese Lanterns grow best in full sunshine so you might want to pot up one of the plants you dig up and set it in a container in full sunshine. I think you'll notice a difference. The only other reason yours would fail to produce berries is if there is no insect activity in your garden (perhaps you use chemical sprays?). More likely, though, your plants just need more sunshine than they are presently getting.
Best wishes with your Chinese Lanterns!
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