Amended returns need to be mailed out and generally take much longer -- it has to scanned, perfected before it can be processed. If you amended a return while your original was being processed, the system will take even longer because a lot of human intervention is required, depending on exact timing of the returns entering the processing stream. You can check the status of processing of your amended return at "Where is My Amended Return" at www.irs.gov or call them.
