Google Sheets – Conditional Formatting Format Cell Color compare to another column cell value

I was trying to change the cell color if the cell value doesn’t in the list of another column using the Conditional Formatting but my formula is wrong so it wouldn’t change the color.
The formula I had tried:

=AC3:AC<0

Desired Output:

>Solution :

Try below formula in CF rules.

=IF($A3<>"",NOT(ISNUMBER(MATCH($A3,$C$3:$C,0))),"")