cubase 5 playback issue

Hey guys i’m new to cubase 5 and I do work with adobe audition generally…
I should work my new project that is sound designing for a short movie on this daw but i got a problem!
When i press space bar for playback it starts normally but sound goes out of sync with video gradually…
Video is editted and exported from premier as a full hd mpeg video 25fps with 48khz sample rate sound but its blank!
audio files are recorded on zoom h4n as wav 48/24…
project setup on cubase 5 is same as video frame rate and audio sample rate…
Is there any thing i missed?
Any solution?
Thanks