Which image you have written to your microSD card (Raspbian image, or Piaware sd card image, or Pi24 image)?
Irrespective of your image, as you are successfully feeding other sites, you already have one of the decoder installed (either dump1090-fa or dum1090-mutability). This decoder will grab the receiver (prostick) at boot.
The rbfeeder can be run in two modes
(1) network_mode=true, and in this case it uses data from already running dump1090
(2) network_mode=false, and in this case it starts its own integral dump1090 which tries to use receiver prostick.
As you already have a dump1090 running & using receiver, the setting network=false results in failure of rbfeeder's built-in dump1090.
Therefore in your case you must use setting network_mode=true.
sudo nano /etc/rbfeeder.ini
The bove command will open file whose contents are given below. Make sure your settings are same as those shown in red.
[client]
network_mode = true
log_file = /var/log/rbfeeder.log
key = xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
sn = EXTRPIxxxxxx
[network]
mode = beast
external_port = 30005
external_host = 127.0.0.1
[mlat]