Finally I could solve that problem!
Kill the Bluetooth-Applet: sudo killall bluetooth-applet
For PIN-Pairing set sspmode to 0: sudo hciconfig hci0 sspmode 0
I opened the simple-agent, so you can edit the code in RequestPinCode Method the if you want to: sudo gedit /usr/local/bin/simple-agent
Start simple-agent: su -c /usr/local/bin/simple-agent