problem sampling on TR using EX-SMPL

[redkeys]

I need to sample a short audio sequence to playback on the TR 88.
The audio is a WAV file which I launched in Ableton and which came out of my laptop into an audio interface and from there into the jack inputs of the EX-SMPL.
The problem is I can't get any recording levels to show up in the sampler although if I turn the volume up in Ableton do get the ADC OVER! message from the TR.
I know there's definitely audio coming out of the interface because I've plugged headphones into both outputs and heard the file.
I've read the TR manual - vol. 1 - pretty thoroughly and I do think the sampling section/chapter is a bit disorganised.
Am I missing something?

[X-Trade]

It's easier to take the file onto an SD card and load it directly.