Gtoolkit and fast trees

 I would like to understand the differences between   tree and fastTree.

 I've got different behavior between tree and fastTree, the second failing with

a subscript out of bounds.

It happens when I expand the root node and select one of the children.

.... it seems that the rootNode cannot find the children... (see below a screenshot).

  What is more strange is that using the same dataset sometimes it works as expected and sometimes not...  I could not reproduce it in a short script (yet).

 Any pointer is welcome

Thanks.