Try changing the formula in cell H4 to read =IS.BLANK($B$3:$B$5)
Then copy and paste the formula to cell H6
By inserting the dollar signs you force Excel to use the cells defined in the formula rather than recalculating them to B5:B7 which is what happens if you just cut and paste the original formula without the dollar signs.
The results for H4 and H6 should then read exactly the same.