The file was created/saved using a newer version of Maple. For example, in Maple 9.5 when opening a document created in Document Mode in Maple 10, the worksheet is blank.
Solution:
If you have access to the version of Maple on which this file was created, save a copy of it in .mws format, and then open the .mws file in your older version of Maple. Note that many features of the worksheet will not be available.
