It shouldn't. I tested it out prior to posting, and it worked correctly for me.
It looks up the value found in cell N5 on SheetA, looking for its match in column C on SheetB, and returns the value from the matching row, from column AE.
Are you sure that you do not have more than one row that matches?
It would be helpful to see your data, to see what the data you are working with looks like (especially your look up range).
MrExcel has a tool called “XL2BB” that lets you post samples of your data that will allow us to copy/paste it to our Excel spreadsheets, so we can work with the same copy of data that you are. Instructions on using this tool can be found here:
XL2BB Add-in
Note that there is also a "
Test Here” forum on this board. This is a place where you can test using this tool (or any other posting techniques that you want to test) before trying to use those tools in your actual posts.