Hi,
You are occasionally getting FALSE because your formula is poorly constructed.
=IF(H5>=250,IF(H5<300,300,0))
If H5 is >= 250 then this bit evaluates IF(H5<300,300,0))
In this part of the formula if H5 is < 300 you get 300 but if it's >=300 you
get zero returned.
But it all goes pear shaped if H5 is <250 because nothing is included in the
formula to evaluate so it returns FALSE
A better constructed formula could be this but I've no odea what your trying
to achieve.
=IF(H5>=250,IF(H5<300,300,0),"Some other output")
Mike