How to get tx_done() after tx_down() ?

I’ve write net filter (under QNX 6.3) that can
catch any packet that goes up (from eth. card en0) on my filter rx_up()
and can send raw ethernet frames to en0 using card tx_down().

It works fine, but there is no call to my filter tx_done()
after en0 tx_down().
Why ?

I tried to create and fill one npkt_done_t strucure
(immediately after npkt_t struct):
npkt_done->done_hdl = filter_funcs.tx_done;
npkt_done->registrant_hdl = filter_reg_hdl;
but it doesn’t work :frowning:.