After page rotate,stamp annotation gets shrunk

Hi,

problem is that stamping works always on the initial page layout.
If you have a portrait format and rotate it to a landscape you won't see a stamp which was set into the right landscape area. With a normalizepage you can avoid this.
If previous stamp disappears, this has to do how you've set the second stamp. Perhaps you've done it with a new contentstream/layer but without transparency - then you won't see previous stamp cause it's under the surface ;-)
To say it short: Functionality works like designed ;-)