Im seeing if someone can help me.

I am doing the low poly man tutorial and Ive made mine a lot different more like an alien but Im still following along and Im at the part where Im rigging and applying skin weights. Im at the shorts section but made mine full pants instead and on the right side I adjusted everything (skin weights) to where Im happy when all the joints bend with the poly pants. When I go to mirror skin weights for it to show up on the left side of the pants joints (L_pelvis, L_hip, L_knee, and L_ankle) I select my pants and click apply for the mirror skin weights to work and nothing happens. My right side still moves perfectly and the left side is still unchanged.

I have it as this:

Mirror Across: XY, Direction is checked for positive to negative,
Surface Association: Closet point on surface
Influence Association 1: Closet joint.

Am I doing something wrong? I tried adjusting the mirror across to any of the 3 and nothing works. Can anybody help me solve this problem?

I am using Maya 2008 on the Mac.

I already posted this in the animation section of the forum but didnt see this forum link until after I already posted.