I have a function

=IF(OR(B9,B10,B11,B12)0,"PBR","PBO")

B9:B12 are numerical values and the cell format is number.

If all the cells are blank the result is #VALUE!

If one of the cells has a number then the formula evaluates correctly and
displays text PBR

If I remove the OR part from the equation and just use one cell (e.g. B9 =
blank)

=IF(B90,"PBR","PBO") then the result is PBO

Why doesn't it work with the OR and blank cells?