The new MT4 Build 600 keeps the indicators and EA files in a different location. So you’ll need to copy and paste them from your current mt4 to the new place. This article by DailyFx.com explains very nicely how to remedy this problem. Thanks Jason Rogers.
Where can I find my EAs, indicators, etc. on MT4 Build 600?
How to Recompile EAs and Indicators on MT4 Build 600
Backing up files on MT4 Build 600
Insufficient Permission to Uninstall MT4