well,when its brand new its a little hard to insert and slide on the splines, but as you use it the sprocket will get in easier.
I also use it in my magnatanium cranks and because the spindle is TI the sprocket goes through much easier after couple of times of removal.
Try to remove some of your SPACERS from the other side of the cranks to line up the chain,otherwise it will wear out the COG or the sprocket much faster
ride on