The following works fine:
=IF(P$5=8,O$5,IF(P$6=8,O$6,IF(P$7=8,O$7,IF(P$8=8,O $8,IF(P$9=8,O$9,IF(P$10=8,O$10,IF(P$11=8,O$11,IF(P $14=8,O$14,0))))))))

But when I try to add one more section to it, I get an error and I can't
understand why.

I am trying to get
this:=IF(P$5=8,O$5,IF(P$6=8,O$6,IF(P$7=8,O$7,IF(P$ 8=8,O$8,IF(P$9=8,O$9,IF(P$10=8,O$10,IF(P$11=8,O$11 ,IF(P$14=8,O$14,IF(P$15=8,O$15,0)))))))))
but I continue to get an error.