This could be due to the following reasons:
Migrating into a later release.
Importing data from third party.
To import vouchers:
1. Enter Gateway of Tally -> Import Data -> Vouchers .
2. Enter the name of the .xml file to be imported, in the Import Vouchers screen.
3. Press Enter to import.
For more details, contact us on 00966-583117703 or visit our website at http://manalpro.com/tally.