One reason could be that there isn't actually an exact match for A2 in the
first column of your array ('Apr-MayMaterial'!A2:D735). Even a difference of
a single space character (assuming you're looking up text) could cause this.

From Excel Help: "When searching text values in the first column of
table_array, ensure that the data in the first column of table_array does not
have leading spaces, trailing spaces, inconsistent use of straight ( ' or " )
and curly ( €˜ or €œ) quotation marks, or nonprinting characters. In these
cases, VLOOKUP may give an incorrect or unexpected value."

Does the final "0" in your formula mean "FALSE"? (I'm not familiar with
that version of the syntax) Regardless, if you leave out the final argument,
or replace "0" with "TRUE", VLOOKUP will return the first match (or nearest
match) it finds. If the final argument is "FALSE", VLOOKUP will only return
an exact match--or "N/A" if it can't find one.

"Lucien" wrote:

I keep getting a #N/A error when using this formula and I don't know why:

=VLOOKUP(A2,'Apr-MayMaterial'!A2:D735,4,0)

Am I doing something wrong within the formula?