autothrottle won't switch on (PMDG 737 NG)?

[Guest petermortelmans]

Which setting need to be made for the autothrottle to work? Which conditions need to be fulfilled? It sometimes just doesn't want to switch on, and the alert light blinks in red, although I'm pretty sure I did all the settings and checks. It must be something I overlooked, but what? It happened several times already.

[downscc 1,327]

Common error is not having the generators on line. Check those on the overhead panel.