Has anyone used the Annotations feature of the Imaging for Windows control?

I'm trying to add an annotation to an image programmatically. I'm trying to show a different character on each page of a multi-page image. Sometimes it works, and sometimes it gives me an "Invalid Annotation Type" error. The code below is basically what I'm doing. The StampText and the Draw Location vary.
I've tried using Annotation groups, and even then, sometimes it works and sometimes it doesn't.

WITH THISFORM.OleImageEdit
	* must display it before annotating it
	.Display()
	
	* stamp it
	.AnnotationType = wiTextStamp

	* with these characteristics
	STORE .F. TO llBold, llItalic, llUnderline, llStrikeThrough
	lcName = 'Arial'
	lnSize = 128

	WITH ThisForm.OleImageEdit.AnnotationFont
		.Bold = llBold
		.Italic = llItalic
		.Name = lcName
		.Size = lnSize
		.Underline = llUnderline
		.StrikeThrough = llStrikeThrough
	ENDWITH
	.AnnotationFontColor = RGB(128,255,128)	&& green
	.AnnotationStampText = 'H'

	* at this location
	lnX = 90
	.Draw(10, lnX)

	* need to save page in order to keep annotation graphics
	llZoom = .F.
	.Save(llZoom)

	* annotations don't show in thumbnails so
	* generate thumbnail to cause annotation graphic to show
	ThisForm.OleThumbNails.GenerateThumb(1, .Page)
ENDWITH

Any and all ideas would be appreciated.

Thanks,
June