TWO PROBLEMS PRE-CUE DDJ200

Hi all!

I bought a DDJ200, and i have problems with audio in "pre-listening".

I've connected all right, with the "split cable" in the box, but everytime in my headphones i can only listen the master track, and not the second one!
This happens just when i play with iphone and "WeDj" app, even if i properly set all: Split output ON, and, as i said, i use the split cable that was inside the box.

When i play with my laptop and with "Rekordbox", pre-cue works perfectly in headphones, but in the master sound i can listen both the songs!!! the right one, but also, in a very low volume, the next one that i might listened only in headphones!
How could i fix all? 

Please help me, and thanks in advance for your support! 

Andrea