removing a treenode and its subnode

[TRAX]

I've got a weird problem: when i try to delete a treenode containing subnodes the last node isn't removed: it gives the object reference not set to ... error.
Here's my code:

Dim lclsSubNode As clsSubNode
For Each lclsSubNode In pNode.Nodes
If Not lclsSubNode.Checked And Not lclsSubNode Is Nothing Then
'if checked don't delete
lclsSubNode.Remove()
End If
Next
If pNode.GetNodeCount(False) = 0 Then
'if mainnode doesn't conatin subnodes anymore, remove it
pNode.Remove()
End If

clsSubNode is a class that inherist of the Treenode class.
When there are two subnode everything works fine, when there are 3 or more i get the error when deleting the last node. So the function crashes in the for loop. Another weird thing is this: I've got a function that deletes 1 subnode only, when i try to delete the entire mainnode (including subnodes) the getnodecount values hasn't changed. So i delete a subnode of a mainnode havinf 3 nodes in total. You'd expect the getnodecount value to be 2 afterwards, but it still is three however the subnode has disappeared of the screen.
These nodes aren't linked to some datasource so that's not the problem.

I'm really out of ideas here, did i overlook something