error Message :" Could not save a copy as " DSC..........." because write access was not granted ".

After processing my images on Photoshop CC 2014, I try to save them, it came back with error Message :" Could not save a copy as " DSC..........." because write access was not granted ". First I thought the CC 2014 version is the  trial version so the usage is limited, but then I try to precess my images on the CS 6, which I bought it and have been using it with no problems before , the same error message " writing access not granted" appears. I use the software on both Window 7 and Mac OS X 10.9.5 and both came back with same errors.