Whenever a user performs a search without a successful match, Natural Search delivers a No Match message. By default, the No Match is "No matches found for your request.". You can modify this message by changing the StringNoMatch property.
2. In the property pane, select the StringNoMatch property and insert the desired text into the right cell.
After building the Help target, the Natural Search tab displays your StringNoMatch property text when a search is performed with no matches.