If you're getting #N/A it's because the MATCH statement can't match your lookup value to its array. E.g., you're looking for the letter "E" in the array "A", "B", "C", "D". How to fix:
If you're doing an exact match (with the third argument as 0), then your lookup value has to be in the array.
If you're doing an approximate, <=, match, your array has to be in ascending order.
If you're doing an approximate, >=, match, your array has to be in descending order.
Based on your second post it sound to me like you are doing an exact match. If you're matching on text, try trimming the value you're trying to match on. Could be extra spaces.