Tvheadend

Hi

I have a problem with nvenc_h264. I see this in log | grep transcode:

2017-09-27 11:00:39.369 [ INFO]:transcode: Could not find requestd lang [pol] in stream, using first one
2017-09-27 11:00:39.370 [ INFO]:transcode: 0001: 1:H264 1920x1080 > H264 640x360 (nvenc_h264)
2017-09-27 11:00:39.372 [ INFO]:transcode: 0001: 2:AC3 > AAC (aac)
2017-09-27 11:00:39.842 [ DEBUG]:transcode: 0001: using audio sample rate 48000
2017-09-27 11:00:39.842 [ DEBUG]:transcode: 0001: using audio sample format fltp
2017-09-27 11:00:39.842 [ DEBUG]:transcode: 0001: using audio channel layout stereo
2017-09-27 11:00:39.847 [ DEBUG]:transcode: 0001: starting audio resampling
2017-09-27 11:00:39.847 [ DEBUG]:transcode: 0001: IN : channel_layout=5.1(side), rate=48000, fmt=fltp, bitrate=384000
2017-09-27 11:00:39.847 [ DEBUG]:transcode: 0001: OUT: channel_layout=stereo, rate=48000, fmt=fltp, bitrate=192000
2017-09-27 11:00:39.931 [WARNING]:transcode: 0001: Detected framedrop in audio
2017-09-27 11:00:40.045 [ INFO]:transcode: 0001: Using preset hq
2017-09-27 11:00:40.047 [ ERROR]:transcode: 0001: Unable to open nvenc_h264 encoder

and these pkgs are installed (centos7)

nvidia-detect-384.90-1.el7.elrepo.x86_64
xorg-x11-drv-nvidia-340xx-devel-340.102-1.el7.centos.x86_64
xorg-x11-drv-nvidia-340xx-340.102-1.el7.centos.x86_64
xorg-x11-drv-nvidia-340xx-libs-340.102-1.el7.centos.x86_64
kmod-nvidia-340xx-340.102-4.el7.centos.x86_64
xorg-x11-drv-nvidia-340xx-kmodsrc-340.102-1.el7.centos.x86_64
xorg-x11-drv-nvidia-340xx-cuda-340.102-1.el7.centos.x86_64

the modules nvidia and nvidia_uvm are successfully loaded, dmesg shows:

61000.536896] vgaarb: device changed decodes: PCI:0000:00:03.0,olddecodes=none,decodes=none:owns=none
[61000.539983] [drm] Initialized nvidia-drm 0.0.0 20150116 for 0000:00:03.0 on minor 0
[61000.540042] NVRM: loading NVIDIA UNIX x86_64 Kernel Module 340.102 Mon Jan 16 13:06:29 PST 2017

[61000.540197] NVRM: PAT configuration unsupported.
[61005.872596] nvidia_uvm: Loaded the UVM driver, major device number 242

the nvidia card is geforce 8400 gs.

tvheadend is tvheadend-4.2.3-87~g5b7886e.el7.centos.x86_64

Why it doesnt work? What i'm missing?

Greetz