I had similar problems. Turns out that when you tell Notes to "Generate HTML
for all fields", you get an extra (hidden) input field for the
Computed-for-Display field, with the same name as the Search field. And of
course, this is empty, which causes the "undefined" result. For now, I have
hidden the search box (in my case, a subform) when I _have_ to use the
"Generate HTML for all fields" option, and the Form is in edit mode.