Clamshell mode not working even after powering off and reconnecting display; external monitor goes black anyway

Hi Mike,

Yes I followed all the procedueres....except for waking the computer using a keyboard click. For obvious reasons one is just inclined to open the top of the MacBook to wake it when the external goes dark...I did that twice, until I realized that very last step was needed to 'wake' it. It worked. Something so simple, easy to overlook I guess.

I did leave the monitors mirrored, fyi, if I don't then all I can access from the external are the resolution settings. This Viewsonic comes pre-loaded with Windows software of it's own and doesn't quite behanve the way my previous external did, but I got it figured out.

Thanks for your response, tho!