The reason for this is the end date in the B4 cell has the value of NA which is the non-date value so resulting in VALUE. If you get the VALUE. The following might solve your problem.
In a new workbook type a 2 in cell A1.
Error go to the next step. The first way to fix the hidden space is to simply delete it. If you still face the excel error message then check out for the blank cells missing formulas or use or special characters2 in cells. Burn to learn focuses on a simple way to solve this problem.