Hey Greg, the first thing to check is the preamp battery in your guitar. Make sure your guitar is passing signal. Trying another cable between the guitar and TWA is worth a shot as well.
If your guitar's output and the cable are good, check the DI Menu on TWA. You'll simultaneously (and briefly) click the parameters and amplitude knobs. Use the parameters knob to make sure it's set to 'TWA and DI' and click to confirm.
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