Why I cant move anything with the 'My Files' app?

I have a problem with moving some files to another folder at the "My Files" app (THIS IS NOT A SD CARD ISSUE). I'm using Samsung Galaxy Ace NXT (SM-313H) with 512 mb ram and 4 gb internal with 800mb free space , android 4.4.2 (KitKat). I did try es file manager but it says "Task Failed".help anyone?

What file are you trying to move?
From where?
To where?

Welcome to Android Central! If the directory you're trying to access is a protected system directory, you won't be able to do it unless the phone is rooted.