Control bones not working properly

[Mattyj]

Hi there just having an issue with my control bones. I have bound my normal bones to the layer containing each pupil of a character, one for right one for left. I have created a head bone and parented each bone to that bone. I created a couple of vertical control bones in the bone layer outside of the character, and parented each to the respective pupil bone, one for the right and one for the left. I then went into bone contraints and selected the control bones for each pupil bone. I go to frame one to test- the right control works ok except I cannot scale at all. The left control bone moves both eyes and eyelids rather than just the left pupil.

Is this a problem others have come across? Any advice would be really appreciated. Thanks.