Rewire and playback problem

[hennestudio]

Im using Sibelius 7.5.1 and Cubase 8 Pro
CPU quadcore 3.2 Ghz 32 GB Ram windows 7

First I start Cubase,then activate "rewire sibelius7.5"
Next I start Sibelius
Both running syncron,
The Problem, when I want to start the playback from ,for example meassure 5 or 9 or somwere later, the playback jumps quickly to a way farter meassure someware 21 or so and starts there.
Starting from the top is not a problem.
Starting somwere from cubase makes no trouble.
It makes it impossible to record somne notes in the middle of of my piece because the coursor jumps elewhere.

Also when I load an mp3 or wave file in the Video window, it plays back fine. But when I want ro record notes while the playback runs, the playback makes noise ,the tempo gets unstable and the mp3 or wave beginns to pitch down.

All I want to do is recording notes on my midikeyboard while a playback is running.
Both ways,rewire or mp3 playback in video window, are not working.