Tabbing out of a text scroll view to another field

I have an app that has many text entry fields, most of them ‘normal’ but in the middle of them is one that has to be text scroll view (so user can enter several lines of text with returns). But I need to be able to tab out of that box; by default pressing TAB will just type in a tab in the text. I tried the below code to detect for a tab key press and jump to the next field, but it doesn’t really work right. It jumps through the scoll view right away. When the user takes the mouse and clicks in, types, and presses tab, the focus correctly jumps to the next field. But they can’t tab going *into the box now, it jumps out immediately.
Any suggestions?

on keyboard up theObject event theEvent
if character of theEvent is equal to (ASCII character 9) then
tell window “main” to set first responder to text field “advowner”
end if
end keyboard up

You can use Ctrl+Tab to get out of a text view.

Thanks Bruce, that will work.
I also was able to add a shift and return key event to jump out, so my users could have 2 options.