Selecting Only next child

Question

Doing a treeview in MVC .

 

Clicking the blue icon expands next node and icon turn green. When I click "Client Alpha", Beta, Gamma or Delta the epansion occurs as expected. But when I click the icon for Issue 1, Issue 1's nodes expand but "Client Beta" is also hidden.

 

In the uploaded source code, I am getting the next div and using toggle() to hide/show.

What can I do to prevent the next "main node" from also hiding? What am I missing?