I got this error DF-DLA-15 at google play when I tried load apps. It started after I reset the phone to factory defaults (at starting the phone push vol+ and menu ).
I then couldn't use google play for days. Until I did go to settings -> Accounts and sync. I modified something there, I removed the other user, and created, and un selected background data and auto sync.
Then google play said that backround data must be on. So after that: google play store was able to load all apps from there.