If you do not include the BASICAuth script described in Configuring ServiceNow to Support the Enterprise Manager ServiceNow Connector, the following error will occur:
In Enterprise Manager: Connection test failed, check oms log file for details. The configuration was saved.
In ServiceNow: No messages are displayed in the logs. It does not accept the SOAP message because it lacks the BASICAuth and thus, no record of it exists.
Solution: Add the BASICAuth script to Script Includes in ServiceNow as described in Configuring ServiceNow to Support the Enterprise Manager ServiceNow Connector