R help - May 2012 - using rcom to control Power Point - problem to set a property

Hi all,

I try to convert the VBA code below to run it from R using rcom and Power Point.
The VBA code creates a shape and will move the handle of the the shape to
another position.
This fails using rcom and I do not understand what I am doing wrong...

### VBA ###

ActiveWindow.Selection.SlideRange.Shapes.AddShape(msoShapeRectangularCallout,
144, 144, 200, 200).Select
With ActiveWindow.Selection.ShapeRange
.Adjustments.Item(1) = 0.0942
.Adjustments.Item(2) = 1.7395
End With

### R ###

library(rcom)

## initializing power point program and slide
ppt <- comCreateObject("PowerPoint.Application")
ppt[["visible"]] <- TRUE
pres <- ppt[["Presentations"]]$add()
slide <- pres[["Slides"]]$add(1, 12)
slide$Select()

## adding the ppt autoform (corresponds to the above VBA code). The last lines
fail for some reason.
doc <- ppt[["ActivePresentation"]][["Slides"]]$Item(1)
rect <- doc[["Shapes"]]$AddShape(Type=105, Top=144, Left=144,
Width=200, Height=200)
rect$Select()
shp <-
ppt[["ActiveWindow"]][["Selection"]][["ShapeRange"]]

shp[["Adjustments"]][["Count"]]  							# there are
adjustment items!!
names(comGetObjectInfo(shp[["Adjustments"]]))  			# there is a
function called Item

# now the code below does not work
shp[["Adjustments"]][["Item"]]       # does not work
shp[["Adjustments"]]$Item(1)         # does not work
shp[["Adjustments"]]$Item(1) <- .9   # does not work -> error

Does someone why this is the case or what I am doing wrong?
Thanks !
Mark

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Mark Heckmann
Blog: www.markheckmann.de
R-Blog: http://ryouready.wordpress.com