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A scientific name would help or a reasonably clear pic. Just in general and depending on when it was introduced it could either not like placement, is not photsynthetic, still acclimating to conditions, etc etc.
Diodogorgia nodulifera is the scientific name. I had it in a 55 gallon tank w/2 175 mh 14k lights. It opened up often in that tank. I recently upgraded to a 92 corner w/ the same lights.
I figured it was and it is not photosynthetic so it will need regular feedings. Might be still acclimating to changed conditions or being moved in general, but you can try coaxing the polyps out by feeding it at night.