farmland server bug?

made a villiger powered wheatfarm(breadfarm) in singelplayer and it worked fine, but when i built a copy on my SERVER the lightlevel on the farmland bugged out. I use a pressure plate to "pop" out the seed when the villiger walks over it and this dont seam to work on the server.

i need a light level at 7 on the one block inside the farm for it to work but i can only get 8(or higher) or 0. so you can either plant crops or you cant because its to dark.