Alt Text for Place Holder

I have a text entry box. If you type in the wrong text and tab (text entry loses focus), you get an error message. Now, tabbing from that text entry box advances the yellow highlight to the Menu button because that's how I have the Tab Order set. What I don't want is a user to tab out of the text entry box and accidentally press Enter because that will trigger the Menu button.

So I created an extra shape, hid it behind the text entry box, and set it immediately after the text entry box in the Tab Order. This way, if the user presses tab from the text entry box, they're not on the Menu button and pressing Enter won't do anything. Hiding it behind the text entry box also serves as a way to let the user think they're still on the text entry box because when they tab, it highlights around the text entry box.

My question is: If I'm using this shape as a 'buffer' between the text entry box and the menu button, does this qualify as decorative? Or would it behoove me to use some Alt Text like: Try Again?