Try the following steps to resolve the error message:
  1. Confirm all dates for depreciation are in an open fiscal period. How to open a fiscal period.
  2. If they do not want to post the disposal amount on the General Ledger they can click through the error messages and leave the transactions as "do not post".
  3. Purge the asset and enter a new asset. How to purge an asset.       How to add a new asset.