Textbox in Word

Evening,

I'm having a little difficulty with a Textbox. Or, more specifically, a TextFrame. In Word. I want to autosize it to the text which is entered, but I can't seem to do so. I can add it ok, as long as I fix the height and width, but then afterwards if I set the autosize property to True, nowt appears to happen.

Any suggestions as to why? Or any other ways to determine how to set the height of the textframe on the basis of the length of the text therein?

incidentally, I should mention that it is on a canvas. It seems to work ok in the bare document.

Cheers

zaza