Problem with Sync

I have installed the endnote X7 (7.7.1) on my Mac(10.10.5), I want to use a shared library, but When I do the sync, the Registration window shows up, and I entered the password correctly and ‘I agree’ to the ‘ENDNOTE END USER LICENSE AGREEMENT’, But there is an error message “EndNote registration could not be completed at this time. Please contact technical support.” and the Sync button keeps grey.

I have tried many times for several days, what should I do???

Many thanks!!! 

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