Thomson Reuters have reported a problem downloading records with publication dates of 2010 or later. When importing records from 2010 or later, the record may have a blank in the Year field.
This problem effects EndNote version 8 to X2.
There is an update available for EndNote X2 (Windows and Mac OS X) from here
The Thomson Reuters EndNote FAQ suggests workarounds for version X1 and earlier, and allows users to register in order to be notified when patches become available.