Filer is a genetic term in the context of the application. Typically Admins refer to windows as Winnas, EMC as NAS and NetApp as a filer in the industry terms. Rather that splash the thread with multiple screenshots I'll let you specify a particular filer before I do but meanwhile let me try to resolve the issue with many configuration issues by describing generic procedures you need to follow to properly test credentials and I'll show you how to save a credential.
To use the APIs for monitoring the various filers the credentials used have to have access to capture access events need to have Admin access to the filer to capture I/O and scan credentials need to have permission to the share and filesystem underneath it or you should expect system error on access (err 5).
To test a credential you should (from the chosen collector machine) be able to mount and traverse the share. The administrator's manual will detail the prerequisites such as a NFS client, Vendor API install (for monitoring) and particular APIs required for connection to each type of filer. The tests in the configuration wizard:
1) try to connect to administer the filer, a successful connection is a green checkmark
2) try to mount the first available non-hidden or excluded share anf pseudo background mount is performed and success is a green checkmark.
Winnas filer requires connection to push install the agent (required for monitoring) as an interactive user able to run WMI (Windows Management Instrumentation) and make RPCs (Remote Procedure Call) to download and install the binaries from the C:\Program Files\Symantec\DataInsight\installers (Default) directory on the desired node. It must then be registered to the Management Server (MS) with the communications keystore certificate for the proprietary communications channel to become active. The C:\Program Files\Symantec\DataInsight\log\winnas_util.log can be reviewed to see the connection and share discovery (Scan). There is a library installed as part of the agent that allows for capture of I/O for events, without an agent scanning can be done agentlessly with appropriate permissions to shares and filesystem hierarchy but no access events can be captured.
If a new credential is required you cna add one in the configuration wizard or use the credential screen to add all new credentials to make them available in the dropdown list. See picture below:
Please reply back on whether this assists you in your configuration or ask specifically which filer you wish the screenshots of and I'll relay that information.
BTW we have some useful knowledgebase articles you can review on the subject as well:
Sometimes the credential fails when it should pass as we only attempt to mount the first available share see - http://www.symantec.com/docs/TECH219377
Symantec Data Insight 4.5 Administrator's Guide http://www.symantec.com/docs/DOC7421
Registration requires an open port for communications - http://www.symantec.com/docs/TECH218926
Missing shares form a filer due to exclusion rules - http://www.symantec.com/docs/TECH221310
The Data Insight console falsely reports that WINNAS filers are unreachable with a “HEARTBEAT MISSING” warning but all other functions of the Filers work as expected. - http://www.symantec.com/docs/TECH226757
Windows Filer scans are failing with error V-378-1312-119. - http://www.symantec.com/docs/TECH221925