Select on Reconcile orders from the main screen see below

Enter your start/end date and select on RECONCILE.  Then select one of the following from the bottom

All Calls/Successful Calls - This will show all Calls that have been synced successfully

Failed Calls - This will show calls that failed to sync.  In this situation you need to RESEND each of these by holding down on each call and selecting RESEND ORDER

Once you have done this, select on SYNC to resend the Calls.