Ive put down a new 12mm ply floor on top of 9mm batons & then altro on top. I have really struggled though fitting the new kombi step ive purchased. I cant seem to fit the step whilst locating all six of the securing screws, i cant get the 3 horizontal ones and the 3 vertical ones all located at the same time. Ive eventually managed to fit the step with just the 3 vertical screws fitted, i was thinking of just using a self tapper in the top to secure it? Is there a special technique to fit these kombi steps?