Fill down Issue

The values below have to be null, not blank or space. Just right click to copy the blank value, click replace values, replace with null. Then fill down. 

--Nate

By using fill down, the null value (not blank cell) are replaced by the previous value, in your case, change your data type (or replace command) into text to change the blanck cell to null then use fill down 

I should trimmed text fist then replaced the value 

thank you for your support