Recently, just after Google started OTA (Over-the-Air) updates for Android 5, we have faced with a problem: applications protected with DexProtector worked fine under purely installed factory image of Android 5, and did not work under some devices that were updated from earlier Android versions via OTA update to Lollipop.
We recommend to update your copy to version 5.0.3, the problem is solved in this release. Do not forget to re-protect and re-publish your apps to application stores.