I have a vlookup formula in spreadsheet A picking up a value in spreadsheet
B. There are 3 possible entries in the column in Spreadsheet B - N,W or C. If
spreadsheet B is not open and the links are updated in Spreadsheet A, then
only the cells with a N in are picked up, if the cell has a W or a C in it
then #N/A is shown. It only picks up the W or C if spreadsheet B is open. If
I change a W or C in spreadsheet B to a N, save it, shut B down and reopen
spreadsheet A then it now picks up the changed value.

I've checked all formats and formulas and nothing is wrong. The only thing
it doesn't like if the letters W or C in this spreadsheet.

Any suggestions on why this could happen or how to fix it are extremely
appreciated.