If "This file cannot be previewed" error displays when using the Export .xls function in the Management Portal on your iPad follow these instructions:
1) When working in the Management Portal on an iPad select the Export .csv button.
2) The software will open as a csv file.
3) Select the document forward button in the top right corner and "Copy" the worksheet program to an installed iPad app, i.e. Numbers or Excel. Numbers is available in the app store for newer iPads for free.
For more detailed instructions please see the following related article: