problems with placing

Ive an issue with MCX, Im working on a project and now I need to place my work.
my problem is that when I use the same coordinates it doesnt fit perfectly.
first image(top down):
ive used the GP wizard for the taxiways(ignore the black textures) and the "place and convert wizard" for the objects.
same corinates for both.
what its suppose to look like is that the small aprons on the sides of the taxiways will be coverd by the objects.

as you can see in the second image the GP and the objects fit perfectly in MCX(the merge was done to show that in MCX and in SKETCHUP they fit perfectly.

any solution?

thanks in advance :)