Tvheadend

Hi all,
I am asking for help setting up TvHeadend on a Raspberry Pi 2. I would like to watch TV with it using a Terratec Cinergy DT USB XS Diversity stick. The Pi's operating system is Raspian (Debian) Jessie, the system is up to date. The DVB-T usb stick is recognized ans (as far as I can see) properly installed, as dsmesg gives:

[    3.977179] usb 1-1.5.1: New USB device found, idVendor=0ccd, idProduct=005a
[    3.986814] usb 1-1.5.1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[    3.999053] usb 1-1.5.1: Product: Cinergy DT XS
[    4.006028] usb 1-1.5.1: Manufacturer: TerraTec
[    4.012954] usb 1-1.5.1: SerialNumber: 071002004989
[    4.210423] fuse init (API version 7.26)
[    5.670012] systemd-udevd[119]: starting version 215
[    7.726967] EXT4-fs (mmcblk0p2): re-mounted. Opts: (null)
[    8.082650] dvb-usb: found a 'Terratec Cinergy DT XS Diversity' in warm state.
[    8.082991] dvb-usb: will pass the complete MPEG2 transport stream to the software demuxer.
[    8.083259] DVB: registering new adapter (Terratec Cinergy DT XS Diversity)
[    8.471656] usb 1-1.5.1: DVB: registering adapter 0 frontend 0 (DiBcom 7000PC)...
[    8.500142] MT2266: successfully identified
[    8.691035] dvb-usb: will pass the complete MPEG2 transport stream to the software demuxer.
[    8.691306] DVB: registering new adapter (Terratec Cinergy DT XS Diversity)
[    8.865896] usb 1-1.5.1: DVB: registering adapter 1 frontend 0 (DiBcom 7000PC)...
[    8.870437] MT2266: successfully identified
[    9.114663] Registered IR keymap rc-dib0700-rc5
[    9.116824] input: IR-receiver inside an USB DVB receiver as /devices/platform/soc/20980000.usb/usb1/1-1/1-1.5/1-1.5.1/rc/rc0/input0
[    9.116880] rc rc0: IR-receiver inside an USB DVB receiver as /devices/platform/soc/20980000.usb/usb1/1-1/1-1.5/1-1.5.1/rc/rc0
[    9.117084] dvb-usb: schedule remote query interval to 50 msecs.
[    9.117106] dvb-usb: Terratec Cinergy DT XS Diversity successfully initialized and connected.
[    9.121103] usbcore: registered new interface driver dvb_usb_dib0700
[    9.294234] gpiomem-bcm2835 20200000.gpiomem: Initialised: Registers at 0x20200000

TvHeadend is working on the Pi, and I see two TV adapters. I can scan DVB-T and TvHeadend finds different Muxes and Networks. However, as soon as I try to play them (from within TvHeadend using the "watch TV" function or with VLC) nothing happens. VLC does find stations in the playlist, but does not play anything. The Raspberry Pi's syslogs loggs error messages of the following kind each time I try to watch a chanel:

tvheadend[569]: tot: invalid checksum (len 8, errors 1)
tvheadend[569]: eit: invalid checksum (len 1675, errors 4)

I kindly ask for help with this problem. Any help would be appreciated. If it is necessary to provide more information, I would happily do that!
Many thanks in advance,
Daniel