Tvheadend

In my configuration I have two different IPTV providers. I added two IPTV networks with one Mux and one Service each. When I try to record from both channels at the same time only the first works, the second gets a "Waiting for stream" message.
Logfiles show 'No input source available' and 'No free adapter' messages.

Feb  5 17:30:31 humpink tvheadend[15235]: dvr: entry 0751046a3db25c0a03816d1bbd16e834 "Brisant" on "Das Erste HD" starting at 2015-02-05 17:13:30, scheduled for recording by "****" 
Feb  5 17:30:31 humpink tvheadend[15235]: dvr: "Brisant" on "Das Erste HD" recorder starting
Feb  5 17:30:31 humpink tvheadend[15235]: mpegts: Das Erste HD in Entertain - tuning on IPTV
Feb  5 17:30:31 humpink tvheadend[15235]: subscription: 0015: "DVR: Brisant" subscribing on "Das Erste HD", weight: 300, adapter: "IPTV", network: "Entertain", mux: "Das Erste HD", provider: "<N/A>", service: "Das Erste HD" 
Feb  5 17:30:31 humpink tvheadend[15235]: dvr: /IPTV/Das Erste HD-Brisant.2015-02-05.17-15-2.mkv from adapter: "IPTV", network: "Entertain", mux: "Das Erste HD", provider: "<N/A>", service: "Das Erste HD" 
Feb  5 17:30:31 humpink tvheadend[15235]: dvr:  #  type              lang  resolution  aspect ratio  sample rate  channels
Feb  5 17:30:31 humpink tvheadend[15235]: dvr:  1  H264                    1280x720    16:9                                 
Feb  5 17:30:31 humpink tvheadend[15235]: dvr:  2  MPEG2AUDIO        ger                             48000        2         
Feb  5 17:30:31 humpink tvheadend[15235]: dvr:  3  AC3               und                             48000        2         
Feb  5 17:30:31 humpink tvheadend[15235]: dvr:  4  TELETEXT                                                                 
Feb  5 17:30:31 humpink tvheadend[15235]: dvr:  5  CA                                                                       
Feb  5 17:30:33 humpink tvheadend[15235]: dvr: entry 93c445991ce93102666290a1d30ae55c "Brisant" on "ARD HD" starting at 2015-02-05 17:13:30, scheduled for recording by "****" 
Feb  5 17:30:33 humpink tvheadend[15235]: dvr: "Brisant" on "ARD HD" recorder starting
Feb  5 17:30:37 humpink tvheadend[15235]: subscription: 0016: No input source available for subscription "DVR: Brisant" to channel "ARD HD" 
Feb  5 17:30:37 humpink tvheadend[15235]: dvr: Recording unable to start: "Brisant": No free adapter
Feb  5 17:30:39 humpink tvheadend[15235]: subscription: 0016: No input source available for subscription "DVR: Brisant" to channel "ARD HD" 
Feb  5 17:30:40 humpink tvheadend[15235]: subscription: 0015: "DVR: Brisant" unsubscribing from "Das Erste HD" 
Feb  5 17:30:40 humpink tvheadend[15235]: dvr: "Brisant" on "Das Erste HD": End of program: Aborted by user
Feb  5 17:30:40 humpink tvheadend[15235]: mpegts: ARD HD in Others - tuning on IPTV
Feb  5 17:30:40 humpink tvheadend[15235]: subscription: 0016: "DVR: Brisant" subscribing on "ARD HD", weight: 300, adapter: "IPTV", network: "Others", mux: "ARD HD", provider: "FFmpeg", service: "Service01" 
Feb  5 17:30:43 humpink tvheadend[15235]: dvr: /IPTV/ARD HD-Brisant.2015-02-05.17-15-1.mka from adapter: "IPTV", network: "Others", mux: "ARD HD", provider: "FFmpeg", service: "Service01" 
Feb  5 17:30:43 humpink tvheadend[15235]: dvr:  #  type              lang  resolution  aspect ratio  sample rate  channels
Feb  5 17:30:43 humpink tvheadend[15235]: dvr:  1  H264                    1280x720    ?                                    <disabled, no valid input>
Feb  5 17:30:43 humpink tvheadend[15235]: dvr:  2  AAC-LATM          ger                             44100        2         
Feb  5 17:30:45 humpink tvheadend[15235]: subscription: 0016: "DVR: Brisant" unsubscribing from "ARD HD" 
Feb  5 17:30:45 humpink tvheadend[15235]: dvr: "Brisant" on "ARD HD": End of program: Aborted by user