1st check if you you did everything right:
- all uv islands have seperate smoothing groups
- the pivots of high and low are matching
- you reset the cage and pushed it by yourself
- for green channel "down" you leave the normalbump shader setting as is, for green channel "up" you turn on "flip green(y)" in the normalbump shadernode
if this all applies and the seam is still there, just restart max..it might work also for you!