When I modify a RAW photo in CS6, I save it as a .psd in Bridge and then as a .tiff, but when I try to save it as a .jpeg it saves it as a "copy" and then when I try to add it to Iphoto, it gives me an error message and says it can't find the original photo and won't display it at all in Iphoto. What am I doing wrong?
The iPhoto part I'm not sure about - that just sounds like a bug in iPhoto.
But It saves as a copy because you have data in the document that cannot be represented in JPEG - so you are saving a copy, not saving all the data in your document.
iPhoto and Adobe do not play well together, you can google this. iPhoto puts images into a hidden packet.