Sort statement

We are trying to update from version 8.1.3.1 to 10.0 and are getting an File error 93 when attempting to sort. The sort statement is shown below. We use 2 separate Select statements for the using and giving files, but they both reference the same physical file. Has something changed since version 8.1.3.1 that prohibits this?

Thanks

David

              Sort PolicySearchSrt
                 On Ascending  Key PolicySearchSrt-Policy-Status
                 On Descending Key PolicySearchSrt-Bitmap-Switch
                 On Descending Key PolicySearchSrt-Policy-Key
                 On Descending Key PolicySearchSrt-Insured
                    With Duplicates In Order
                       Using InPolicySearch
                          Giving PolicySearch