crop / trim inserted picture

[GeoffL]

I'm a newbie at visio and am trying to crop or trim an imported picture in a
manner similar to that described in MS KB article 258458, employing the
"fragment" operation. I am trying to crop the picture to an elipse-shaped
area. Although using fragment with two vector shapes works as expected, when
I try using a vector shape to trim a picture, I end up with a filled vector
elipse shape and the picture vanishes.

Perhaps this is due to the desired operation only working with vector shapes?

Any suggestions or enlightenment would be most welcome.

Thanks in advance!