Why does my holly not produce berries?

Hollies (Ilex) require both male and female plants for berry production. Berries are only produced on female plants. One male may pollinate several female plants. Only large leaf hollies (‘Blue Princess,’ ‘China Girl,’ etc.) are planted for berry production. Small leaf hollies (‘Green Luster,’ ‘Hetzii,’ ‘Northern Beauty’) are used for foliage effect and not for the black berries they produce. In order for berry production to occur, the correct pairs of male and female plants must be planted together. ‘China Boy’ will pollinate only ‘China Girl.’ Any of the male blue hollies (‘Blue Prince,’ ‘Blue Stallion,’ ‘Blue Boy’) will pollinate any of the female blue hollies (‘Blue Princess,’ ‘Blue Maid,’ ‘Blue Girl’). ‘Golden Girl’ is pollinated by any of the male blue hollies.