|Let's start with the fact that your OS (Windows NT 6.1) has nothing to do with this. |
VLOOKUP is an Excel function, unrelated to the OS version.
Next, you said:
I know the VLookup formula.
You might, but we don't, nor do we know how either of your spreadsheets are laid out.
Since we can't see your workbook from where we're sitting, there is no way for us to offer any suggestions related to your issue.
Perhaps if you posted some example data, along with the formula you are using and the expected output of that formula, we could be of some assistance.
Before posting any example data, please click on the following line and read the instructions found via that link.
Click Here Before Posting Data or VBA Code ---> How To Post Data or Code.