Change you code to:
If object collision(15,36)= 1 then position object 36,X#,100,Z#
Because object 15 collides with object 36, not the other way around (I think). Also, if your gonna arrange more collisions, use object collision(15,0) which will return the value of any object object 15 collides with, i.e if it collides with object 36, print object collision(15,0), will display 36. This make it easier to use if..then to organize collision, rather than repeatedly check for collision for each separate object.
Whatever I did I didn't do it!