I am attempting to use Excel (2013) to look up whether the value 1 turns up in a given set (using the CHOOSE() function, then, if so, printing the value in the cell directly to the right of it using the VLOOKUP() function. Why would this formula yield two different results in different cells when the formula itself is identical?

=IF(CHOOSE(1, $A$4:$A$17) = 1, VLOOKUP(1, $A$4:$C$17, 2, FALSE), "?")

Cells V4 to V7 in my sheet all have the exact same formula (the one printed above), yet they are returning different values. V4's returned value is the type I would like (i.e., the value of cell B4, which is a number), yet the others are returning "?". Why is this and how can I fix it? Thanks in advance for any help.