[vdr] Diseqc dosen't work with dvbscan

[Rocky]

I am in Asia and I have a Diseqc (should be Compatible with 2.0 version)
        which connect with 4 Satellite, LNB1=105.5 LNB2=115.5 LNB3=138.0
        LNB4=146.0. And the DVB-S card is Twinhan 1020A.
        
        Everything hardware is working well under Windows system, and
        now I want
        move it to Linux.VDR has been successfully setup which I can use
        it
        watching LNB1 channel without any problem. ( I use dvbscan to
        scan
        generate the channel.conf)
        
        But, when I want add LNB2 or LNB3 and 4's channel, it looks
        dvbscan can
        not switch to them and tuning. I have spend lots of time Google
        the
        answer but can not find any useful solutions.
        
        The problem simple description is that the command:
        
        >dvbscan /usr/share/dvb/dvb-s/AsiaSat3S_C-105.5E -l 5750 -s 0
        
        using '/dev/dvb/adapter0/frontend0' and
        '/dev/dvb/adapter0/demux0'
        initial transponder 4000000 H 26850000 3
        >>> tune to: 4000:h:0:26850
        DVB-S IF freq is 1750000
        
        >dvbscan /usr/share/dvb/dvb-s/AsiaSat3S_C-105.5E -l 5750 -s 1
        
        scanning /usr/share/dvb/dvb-s/AsiaSat3S_C-105.5Escanning /usr/share/dvb/dvb-s/AsiaSat3S_C-105.5E
        using '/dev/dvb/adapter0/frontend0' and
        '/dev/dvb/adapter0/demux0'
        initial transponder 4000000 H 26850000 3
        >>> tune to: 4000:h:1:26850
        DVB-S IF freq is 1750000
        
        it looks response the same result(channel list) even if I use
        different
        "-s N" parameter.
        
        But the command:
        >dvbscan /usr/share/dvb/dvb-s/Asia6B_C-115.5E -l 5750 -s 1
        
        scanning /usr/share/dvb/dvb-s/Asia6B_C-115.5E
        using '/dev/dvb/adapter0/frontend0' and
        '/dev/dvb/adapter0/demux0'
        initial transponder 3840000 H 27500000 3
        >>> tune to: 3840:h:1:27500
        DVB-S IF freq is 1910000
        WARNING: >>> tuning failed!!!
        
        If, I un-plug the line from LNB2 and plug into the LNB1 on my
        Diseqc,
        above command will successful find channel too.
        
        I try to modify the diseqc.conf file, but it looks only worked
        for vdr
        not for dvbscan...
        
        So, what can I do and any suggestions?
        
        Regards,
        
        Rocky.Lee