This error is only in InDesign CS6.
Background:This is due to the new feature in InDesign called Alternate layouts.
1. Open your pages palette window in InDesign (Window > Pages)
2. Click on the text above the 1st page in the palette - See screen shot attached. (you need to triple click to get in this text box)
3. Rename the page layout to 'iPad V' for portrait, if you are doing landscape work you would use 'iPad H' (Case sensitive).
4. Save your work and then do the export as normal.
Note: All InDesign CS6 files will now have to have this naming convention.
Information is here in our documentation: