Thanks for your support. I found out the issue and resolved with my old code
itself.

As I told you I kept the listbox2 as hidden, but unfortunately I made its width
to '0'. That's the issue I got this error. But now when I was working on all the
tools I kept slowly and steadily I found this and increased the width of
listbox2 to 40 and hide it behind the listbox1. Now it is working as phantastic.

Thanks for your support. I think I may need to use the columns function in the
listboxes in later. If I use then I'll use your suggestion.