Since Android 4.4 KitKat, apps cannot store data on the SDCard like they used to. Android apps can still read SD card data, but they can only write data in their own dedicated folder.
If you would like to save and store your data on SDCard, make sure you created the following folder structure on your SDcard and specify it as a path to save your data to:
Android/data/com.perpetuumsoft.mobidb (if you are using a full MobiDB version)
Android/data/com.perpetuumsoft.mobidb.lite (if you are using a Lite version)