I'm assuming that the file you are talking about is a VI. Do you get any kind of message when you try to open it? Does the VI have a diagram? A diagram is required to open a VI in newer version of LabVIEW so that it can be recompiled.
The error means exactly what it says. The VI you want to open is a LabVIEW 8.2 version and you only have version 7.1. You can open VIs that were created with an older version of LabVIEW but you can't open VI's created with a newer version. You can download an evaluation version of 8.2 if you want to view it but you could only save it for 8.0. You might want to make a request to the forum to have someone save it as 7.1 for you. I only have the 8.2 eval version myself so I can't do it for you.
File>Save with Options>Save for Previous. If you have anything in a newer version of LabVIEW that did not exist in the previous one, the save for previous will fail.
