[button] is null or not an object

[LacrosseB0ss]

So, I have this pretty little form as an asp page with Javascript running on the page. The page has numerous objects of all types, shapes and sizes. I recently added a tree view to the form. In order to populate the tree view from a database I had to link the form to a VB Class.

Since doing this, whenever I click a button that works with a listbox or textbox, I get the following error:
{name of object} is null or not an object

Funny thing is, this code worked fine before adding the VB Class. There are only 3 objects on the page where this happens: 2 listboxes where if an item is double clicked or a button is clicked, it gets added to another list. AND a button that adds whatever is entered in a textbox to a list.

The line I THINK is causing the problem is this one at the top:
<%@ Page Language="VB" autoeventwireup="false" CodeFile="UDuser_form.aspx.vb" Inherits="UDuser_form"%>
Any help anyone can offer would be greatly appreciated.
LB

ps: sorry if this is the wrong place for the post. The error shows up in javascript so I assumed here was good.

[acoder]

This is usually caused by not being able to find the button/text box/form object. Make sure the object in question is referenced properly, e.g. by its ID.