Can't delete photos from my iPod 2 even following advice in your forums (as delete button is always brayed out)

I transferred photos to my iPad 2 from my iMac running Lion. I want to delete these photos, but when I click the action arrow in ten antic photo app and select a photo the delete button is grated out. Even the folks in the Apple store couldn't delete. I can delete photos that I have synced from iTunes by in checking they album on the Mac and doing a wired sync. But I can't get the photos I transferred using your app. Please help.