Forms :: Tree Hierarchy - Not Working Properly?

i have created a tree hierarchy....when the user clicks on any node,that particular form will open....But there is some problem...i click on form A,it opens.,...then i exit that form via a exit button on the toolbar....and then I click on form B on the tree....but first the form A only opens...and then again i exit form A, then form B will open..

i have written the following code in when_tree_node_selected trigger :

if condition then
call_form(path,no_hide,do_replace);