Error 7 is the "file not found" error, which means that LabVIEW can not find a VI at the specified location you have given it. Can you run the VI in LabVIEW 7.1 without errors? The is a Knowledgebase on this issue as well, which I have linked here. Basically, you just need to make sure that you are not moving files around after you are making the upgrade of your VIs. This applies for DLLs, too, if you are using any. If your VI runs in LabVIEW 7.1 without any trouble, then perhaps you are attempting to include support files with your application that are not at the location you specified. What is the full error message? It may give you a clue as to what VI/DLL LabVIEW can not find.
Kind Regards,
E. Sulzer
Applications Engineer
National Instruments