How To Day/night shades The round, plastic piece that attaches to the wall and holds the strings in place will not grip the string. Screw is free spinning

[clodhopper]

Day/night shades adjustment. The round, plastic piece that attaches to the wall and holds the strings in place will not grip the string. Screw is free spinning. Any suggestions for anchoring the screw?

 

[Gronk]

I have used a plastic concrete wall anchor. Push it into the screw hole and try the screw. I have also had to tie the strings in such a way so that the spool piece doesn't turn also.