I explored an assembly, I had a simple code to get the names of the parts I wanted.
Dim oSel as Selection
set oSel = CATIA.ActiveEditor.Selection
oSel.Search "type=*,all"
On the tree, I saw all the parts being selected. However, when I tried oSel.Count, it returned 0 so I could not loop through my selection to get the names of the parts selected. Not sure what I did wrong.