Issues with [dynamic] list' remove at for tree instances

Hi thank you first of all for even taking time to look at this : to start things off read this link please http://answers.unity3d.com/questions/418587/why-does-my-tree-script-not-work.html

Now colliders get created over trees in world space : trees with no terrain tree colliders + the collider script attached to those invisible trees works perfect I get my logs fine no problem . Now I have the problem of removing the tree's I wrote a script the ideally is the only way from what I under stand ... One script that creates the tree prefabs that has a function attached to that script which gets called from the cutting object script attached to the newly created tree prefab.

The problem is I have no clue, only some of the tree renders remove from the active terrain, meaning I can cut all the trees ... there invisible object destroys but the actuall tree's in the terrain data do not ... well something like 4/10 work they destroy from the terrain ... by using removeat(treeid)

I've looked around post and found exactly the same method on doing this .... Why am I having problems though ?