TreeView.nodes Sometimes Returns An Empty Node Collection?

treeView control which has been plaguing me for the last few days.

I'm not exactly sure what is causing this problem to arise, so I will just explain what my program is trying to do.

I am building an application which will have plugin support. I have created a Plugin interface, which is implemented by each plugin, as well as a host interface, which is implemented only by the host application.

Each plugin has an Action subroutine, and when finished, it is supposed to call the ExecutionComplete subroutine in the host interface.

Now, onto the problem. I have a treeView on the host form, which has several nodes in it. If I create a button on the form which displays a message box with treeView.nodes.count, it shows up fine, and everything works as expected. If I attempt to display the same messagebox from the ExecutionComplete subroutine, it also gives the correct number of nodes.

This is where things get a little weird. I have implemented a save feature into my program, so you can save and load data. For some weird reason, if you have loaded the data from a file, rather than adding each node manually, it now returns an empty node collection ONLY if I try to access it from ExecutionComplete. If I try to access the nodes from a button, it still returns the correct values!

What could it possibly be about the ExecutionComplete subroutine that makes it return a value any different than what is returned when the exact same code is placed in a button click event? And why does it only happen when I've loaded the data from a file? I just don't understand how loading it from a file is any different than them adding the nodes manually. The nodes are definitely being added, as I can see them, and the button click event can also see them. Also, ExecutionComplete is obviously able to read the contents of the treeView, because it works just fine if the user has set up the treeView manually.