How to Fix V2015.12 C3/C4 Xentry Activation Fail

When activate Xentry, Star date and Finish date should be 2012-01-01 and 2020-01-01.
While I activate it, it shows dates as picture

After I input a new Startkey and click "Save", it shows

1.Set laptop's date as current date.

You can just search C:\Documents and Settings\All Users\Application Data\LicDir
then delete those two files