How to sync with EndNote Web

Hi all,

unfortunately I’m having a somewhat similar problem with sync, but not due to authencitation problems. See below my error message:

Sync Details
Sync was last run: Wednesday, August 12, 2015 at 11:05:18 AM +0200
Sync Status: There are changes that need to be sent and received.
Error Code: Server.invalidInput
Error Message: Server.invalidInput - This reference is already expunged

Local Sync Library
Library Name: Ecologia.enl
References: 5734
Groups: 5
Group Sets: 2
Attachments: 5341
Username: dbprovete@gmail.com

Online Sync Library
Serial Number: 5091797072 (Premium until December 31, 2015)
References: 10454
Groups: 5
Group Sets: 2
Attachments: 457 (434.88 MB)

Sync Limits
Number of References: 1000000 (989546 can still be added)
Number of Groups: 5000 (4995 can still be added)
Number of Group Sets: 5000 (4998 can still be added)
Attachment Storage: Unlimited

I’d really appreciate if you could help me solve it. 

Thank you