0967bf21_Lotus_Notes_Traveler_8_5_2__Steps_to_Resolve_Error
[Error Number] 11 [Error Message] Record not found during modify/remove [Notes] Sync client could not locate the record referenced by the server in a sync operation such as modify or delete. [Steps to Resolve Error] 
As in the steps described for error 10 the user can always perform a manual sync. This error is produced for information purposes but the system is basically working fine.
Lotus Notes Traveler 8.5.2
Steps to Resolve Error