Walls and Ceilings - Ceiling register

I am trying to replace an old ceiling register, but the screw holes in the new register are not lining up with the holes already in the ceiling from the old register. When I screw in the new screws, there is nothing behind the drywall to screw into. What do I do now?

Thanks for your help,
Barbara

If it's a normal-sized register, plastic anchors can be pushed into new drywall holes to screw into. Should hold it.
If it's a large register, you may need molly bolts (have spring-loaded, fold-back wings that push through and clamp the back of the drywall). Have to install these in register before installing on ceiling.
You might try probing with an icepick to see if you can use a longer wood screw to reach framing around the register.
Good Luck!