How do I make the defenders stand still?

[Embiss]

I am trying to design an assault scenario. The WP is carefully positioned In the tree line, Nice fields of fire over the valley floor. Lovely looking ambush. Nice spot to watch and wait....Nato advances towards them.

I played it through once as WP and it worked well, Nato went exactly where I wanted them to and ran smack into the ambush.

Then I Played it as Nato. I moved cautiously forward, knowing full well that the tree line was bristling with T72's and all of a sudden....Whallop!

Scores of T72's come screaming across the valley floor and smash right through my recon elements. If the main force been there the WP might have been in trouble but, the main force isnt due for another hour and by that time these T72's will be in France.[:D]

How can I make them stand and fight?

(although I have to hand it to the AI, It suprised me with its aggressivenes and I think its probably going to whup me if I play it through all the way!!)