Block wont detect light

My plant block wont detect the light properly, if the light is 0, set it to one state, then if its any light at all change its state again, the plant is stuck in 0 light mode, note that the plant doesn't make light, but i don't get how its not detecting it, the procedure goes like this: IF get light level for a block at x y (y=1) z = 0 DO replace block with second state. and the other state has the same thing, just with a NOT at the light detection.

Anything helps.