Answer: Berri Magic is a combination with both male and female (Blue Prince and Blue Princess) growing in the same pot. The foliage is slightly different between the two but very well matched.
This means you should have a male for every female in matched pairs. For fruiting you would only need a male for every few females, so lack of male plants is probably not the problem.
In order to have fruit, the plants must bloom. The flowers on holly are quite small and you are not necessarily going to notice them unless you carefully observe the plant. To tell the difference between male and female flowers you need to look closely, the female blooms have a round bulge at the center which will eventually become the berry if all goes well.
Lack of fruiting can be caused by a variety of factors but the most common would be winter cold damage and pruning. Hollies bloom on old wood that grew the previous year and the flower buds are on the plants during the winter.
Excessive cold can damage the flower buds, although in your area that should not be a consistent problem unless possibly due to wildly oscillating temperatures in winter/spring such as had this past year (your zip code places you in zone 6B.) If there is winter dieback caused by wind or cold exposure, this would also damage flower buds.
Pruning to remove damage or to control size will also limit blooming. Keep in mind that the flower buds are set during the summer for the following season.
Another reason for lack of fruiting can be poor weather conditions or lack of pollenizer insect activity at the time the plants are blooming. This would prevent berry set.
Yet another reason for poor fruiting can be poor growing conditions such as drought that cause the fruit to drop prematurely. Also, young plants will bear lightly compared to established plants. Finally, new plants can take a few years to settle in and become established and bloom and fruit their best.
I hope this helps you trouble shoot.
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