Improper BER running flowgraph example from GNURadio Wiki

Hi all,

I am not sure if this is already discussed or if I am missing something but here is my question - when I run a flowgraph that I put together with the transmitter-receiver example from the Gnuradio Wiki, I get inconsistent BER readouts. BER also seems to change when I change either packet length or the modulation parameters of payload.

The connection between the TX-RX blocks is via a wire and not a channel model, so I assume the BER should be close to nil?

Thanks in advance :)