Endnote X6 smart group bug

The smart group of Endnote X6 can recognize the keywords I set, and include certain pdf file when I add annotations to the pdf  file with adobe acrobat. However, if I remove the annotation from the pdf file, the smart group still contains the reference. Please fix this problem.

I come up with two proper ways to fix this problem

1.Re-index all the pdf files per 5 minutes or let user manually re-index them using a button

2.Monitor pdf file changes like dropbox, re-index inmmediately after each change