Tvheadend

Hello,

i have an raspbmc :

I have this usb tnT USB TNT Volar HD Green (A835B)

and i have this error with tvheadend :

pi@raspbmc:~$ tvheadend -s
2014-07-04 20:38:29.190 [   INFO] charset: 138 entries loaded
2014-07-04 20:38:29.210 [   INFO] linuxdvb: adapter added /dev/dvb/adapter0
2014-07-04 20:38:29.221 [   INFO] CSA: Using 32bit parallel descrambling
2014-07-04 20:38:29.223 [   INFO] epggrab: module eit created
2014-07-04 20:38:29.225 [   INFO] epggrab: module uk_freesat created
2014-07-04 20:38:29.227 [   INFO] epggrab: module uk_freeview created
2014-07-04 20:38:29.228 [   INFO] epggrab: module viasat_baltic created
2014-07-04 20:38:29.270 [   INFO] epggrab: module opentv-ausat created
2014-07-04 20:38:29.273 [   INFO] epggrab: module opentv-skyit created
2014-07-04 20:38:29.276 [   INFO] epggrab: module opentv-skyuk created
2014-07-04 20:38:29.287 [   INFO] epggrab: module pyepg created
2014-07-04 20:38:29.289 [   INFO] epggrab: module xmltv created
2014-07-04 20:38:29.298 [   INFO] epgdb: loaded v2
2014-07-04 20:38:29.300 [   INFO] epgdb:   channels   0
2014-07-04 20:38:29.301 [   INFO] epgdb:   brands     0
2014-07-04 20:38:29.303 [   INFO] epgdb:   seasons    0
2014-07-04 20:38:29.305 [   INFO] epgdb:   episodes   0
2014-07-04 20:38:29.307 [   INFO] epgdb:   broadcasts 0
2014-07-04 20:38:29.309 [   INFO] dvr: Creating new configuration ''
2014-07-04 20:38:29.311 [WARNING] dvr: Output directory for video recording is not yet configured for DVR configuration "". Defaulting to to "/home/pi". This can be changed from the web user interface.
2014-07-04 20:38:29.316 [ NOTICE] START: HTS Tvheadend version 3.9.988~gfa10998 started, running as PID:7439 UID:1000 GID:1000, CWD:/home/pi CNF:/home/pi/.hts/tvheadend
2014-07-04 20:38:29.318 [   INFO] mpegts: 0 - tuning on Avermedia A835B(3835)_1 : DVB-T #0
2014-07-04 20:38:29.326 [  ERROR] linuxdvb: Avermedia A835B(3835)_1 : DVB-T #0 - failed to tune [e=Invalid argument]
2014-07-04 20:38:29.328 [WARNING] mpegts: 0 - failed to start on Avermedia A835B(3835)_1 : DVB-T #0, try another

what do u think please ?