Dear Ken
Further testing of the data seemed to indicate that the dataset you were trying to access with Adagio Ledger was one that was being used with a version of ACCPAC GL prior to 6.1A - which would make it incompatible.
When testing, trying to open the data with ACCPAC Plus V6.1 ~ 7.0 gave a similar error initially - "Data is incompatible with this version of General Ledger....Convert - Exit".
Once the data was converted to V6.1A of ACCPAC Plus GL, Adagio opened it no problem. This leads to more specific questions on your exact procedures with this dataset...
Prior to opening this dataset with Adagio - did you actually do the deletion of the 15 accounts and year end closing with ACCPAC?
Finally, using the data we were sent, I was unable to open it with Adagio Payables, as the .new data did not exist. I could, however, open the .dat dataset with Payables no problem, subsequently opening Ledger from the it's 'Adagio' menu option, so either we were not sent all the data - or you opened the .dat Company with Payables, and thus were in that dataset with Ledger, not the .new Company.
This leads us to the following questions - had this .new dataset ever been used with Adagio? (I would find it very surprising if this dataset was created with Adagio and you were able to open it with an older version of ACCPAC Plus GL (e.g. 5.0) - afterwards.) Hypothetically, if you were actually able to do this - certainly Adagio would not be able to open it afterwards, thus the error "Corrupted data or unknown version. Unable to continue.".
Adagio Ledger is compatible with ACCPAC Plus GL versions 6.1 ~ 6.5 only.
Regards