404 Error When Calling vbEnter Event Listener

I am doing a simple thing, I have a button in a page, and I am adding Navigate to another page (in same flow) action on ojAaction event of the button. Then in the target page, I added an event listener for vbEnter. However, some how the page does not identify this event listener and throwing error "Failed to load action chain vbEnterChangeListener Error: ... HTTP status: 404". Any idea why this is happening?

Thanks in advance.