No Signal while scanning with DiseqC

Hi,
I'm using Mediaportal 1.2.1 with TBS6981 driver version 2.0.1.1. Unfortunately the scan is not working. It always returns "no signal". In some cases it works, sometimes on Astra, then on Hotbird. I couldn't distinguish when which sat works. My setup worked once with "Simple A" for Astra and "Simple B" for Hotbird in the MP configuration dialog.
I now downloaded DVBDream to see if the problem is in MP, but even DVBDream shows me the same results => "no signal". Other receivers work fine on the same cable.
Please let me know which log file I can provide for analysation.
Thanks for your help!
I'm using Mediaportal 1.2.1 with TBS6981 driver version 2.0.1.1. Unfortunately the scan is not working. It always returns "no signal". In some cases it works, sometimes on Astra, then on Hotbird. I couldn't distinguish when which sat works. My setup worked once with "Simple A" for Astra and "Simple B" for Hotbird in the MP configuration dialog.
I now downloaded DVBDream to see if the problem is in MP, but even DVBDream shows me the same results => "no signal". Other receivers work fine on the same cable.
Please let me know which log file I can provide for analysation.
Thanks for your help!