I am adding icons to buttons on a drawing tool using 16 pixel icons from the ArcGIS icon collection supplied by the Developer's Kit (C:\Program Files (x86)\ArcGIS\DeveloperKit10.0\Icons). However, not all of the icons are getting added to the buttons. I've tried using the icon or an imbedded image using a base 64 data URI (converted using this site) but neither works.
I've put an example here, with the polygon and extent buttons not getting their icons added. Any ideas why the two aren't showing up?