on returnkey doesn't work

[Joe Lewis Wilkins]

Back, again with what could be a pretty stupid question, and...
this seems like a pretty elementary feature that should work, but  
doesn't - for me - right now.
Thoughts?

I've put the following into a card script and then tried it in a  
field script that would have an insertion point or some selected  
text. Essentially, I'm trying to identify which of the 45 text fields  
on a card is the one in which the user has just entered something, so  
that I can use the return key to go to the next field; the tab key  
works fine in this regard, but I'd like the return key to do the same  
thing. Each of these text fields only uses the first line, but if the  
return key is pressed now, it goes to the next line. Perhaps I should  
be using a different type of field; maybe a label instead?

on returnKey
    -- do anything; I tried a beep and as the dictionary said: go  
next cd; nothing happens
end returnKey

Then in a field
on returnField
   -- ditto
end returnField

TIA,

Joe Wilkins