Annotation ellipse with facealpha not possible?

Hi,

I'm trying to annotate a plot with a ellipse. I'm using the graphic tools to draw the ellipse. But I'm not able to set the FaceAlpha value for the ellipse. The error is:

Error using scribe.scribeellipse/set
The name 'FaceAlpha' is not an accessible property for an instance of class
'scribeellipse'.

It works perfectly for rectangles... :-(

I'm using the following command to set the FaceColor:

   set(gco,'FaceAlpha',0.5)

Any help will be appreciated, thanks