Audacity don't record

I am new here and I use Audacity.
I am trying to use audacity for recording from analog tapes to digital files.
I am using one Analog to digital converter one interface firewire and one digital to analog converter for monotoring.
The problem is, in the pc the audacity recognises the reconding spdif conetion the output spdif for monitoring but it don´t recognises the sound, can someone tell me why? The firewire is one eco audiofire 2 and the sound passes from the AD converter to the Da converter via the eco audiofire 2 but it don´t reaches the audacity editor for recording.
thank you,

FireWire? Are you on a Mac?

I’m trying to follow your sound pathway and I can’t. You should have one device doing the A to D and that plugs into the computer for recording. Plug the headphones into the computer and set Audacity to let you hear the show.

I think you have way too many boxes and cables and conversions.