Audacity flickers but does not record

My Audacity program flickers but does not record - the sound is from a Marantz amplifier RX 173 AV and is plugged into the line in portal.

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My Audacity program flickers

What’s flickering? Are you talking about the dB meters? What are the meters reading?

Does the cursor move when you click Record? Do you get a flat line instead of a waveform?

…plugged into the line in portal.

Connected to tape-out or line-out from the amplifier? Are you sure you’ve got a signal coming out? Do you have anything else to plug-into to check that? (Amplified computer speakers, or your TV, etc.?)

I assume you’re using a desktop/tower computer with a regular soundcard? (Line-in should be color-coded blue.)

Have you selected Line-in as your [u]Recording Device[/u]?