What often happens is that when you are in the recording page (see the tape reel) and place a trigger, you place a normal trigger. What happens then is as your pattern loops back to step 1, the recording processing is restarted and if you have no input, you will be recording silence over your previously (good) recording.
The easiest way to verify you are doing things correctly is place a trigger on step 1, then hold Function and pres the same trigger again. The LED should turn solid yellow. This is a one-shot trigger. Until you are really comfortable with how the OT works, this is usually the best way to start. Oh - while you are in this page, set RLEN to 16 or something smaller than MAX.
Once your pattern loops through that first bar and goes back to step 1, no additional recording will take place, so you can place regular Play triggers (in the normal (non-recording) pages)) and hear the sample.
The other thing to check is to double-click the track button, then press Function+Edit to edit the sample. You should see the waveform and be able to hear it by pressing Function+Yes.