"Can't export multiple files"

I’ve used audacity successfully on eight albums thus far. However, on the latest one, after entering labels for the songs and normalizing, when I tried to Export Multiple a pop-up window told me I couldn’t export multiple files. It said:

“If you have more than one Audio Track, you can export each track as a separate audio file”

“If you have a Label Track, you can export a separate audio file for each label in that track. You can have more than one Label Track, but files will only be exported for the uppermost Label Track”

“This Project does not meet the above criteria for exporting multiple files”

Don’t know what I did wrong and have no idea of how to fix it. Any help will be greatly appreciated. Thanks

Check that your audio track(s) are not muted.