Sync is not possible

I would like to sync my references at myendnoteweb dot com.

However, if I click “sync status,” it says, "

Sync Details
Sync was last run: Never
Sync Status: There are changes that need to be sent.
Error Code: Server.AuthenticationToken.invalidUserCredentials
Error Message: The username/password specified is not valid.

Local Sync Library
Library Name: My EndNote Library1.enl
References: 84
Groups: 2
Group Sets: 1
Attachments: 1

Online Sync Library
Serial Number: Unable to contact the online service.
References: Unknown
Groups: Unknown
Group Sets: Unknown
Attachments: Unknown

Sync Limits
Number of References: Unknown
Number of Groups: Unknown
Number of Group Sets: Unknown
Attachment Storage: Unknown


How can I solve this?


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