opening raw files in elements 10

[jspaughton]

I am trying to follow the tutorial in August DCW magazine to merge two photos in elements ten. I have completed stage one and gone to open image. The instruction then is to go to file, open recent and re-select the original file to open in camera raw again. However, nothing happens and the file will not re-open so that I have the two images. Can anybody throw any light as to why this is?