Hey there, no worries at all—basic issues can feel the most frustrating when you're stuck! Let’s break down systematic checks to figure out why your VLOOKUP isn’t working in that one sheet, even when others with identical setups work fine:

• Check for hidden whitespace or special characters
  Sometimes lookup values have invisible spaces (like non-breaking spaces CHAR(160) instead of regular spaces) or tiny special characters that prevent matches. Test by wrapping both your lookup value and the source lookup column in TRIM(), like:
  =VLOOKUP(TRIM(A2), TRIM($C$2:$D$100), 2, FALSE)

• Verify the exact match argument
  Double-check that your formula uses FALSE (or 0) as the fourth argument. If you accidentally used TRUE (or omitted it), VLOOKUP will try approximate matches, which only work if the lookup column is sorted. Even if your data looks sorted, subtle inconsistencies can break this.

• Check for data type mismatches
  If your lookup value is a number stored as text (or vice versa) while the source column uses the opposite type, VLOOKUP won’t recognize matches. Use ISTEXT() and ISNUMBER() to test both the lookup cell and a cell in the source lookup column. Fix it with VALUE() (text to number) or TEXT() (number to text) as needed.

• Confirm your lookup range references
  Even if you think it’s identical to working sheets, check if the range is correctly anchored (using $ for absolute references) and that it includes all relevant data. Hidden rows or accidentally truncated ranges can cause unexpected failures.

• Rule out merged cells in the lookup column
  Merged cells break VLOOKUP because it only recognizes the top-left cell of the merged range as the reference. Unmerge any cells in your source data’s lookup column and test again.

• Check for circular references
  Rare but possible—if your VLOOKUP references a cell that depends on the formula’s result (directly or indirectly), Excel might suppress the output. Go to the Formulas tab > Error Checking > Circular References to check for this.

• Test with a simplified formula
  Create a small test table in the same sheet with just 2-3 rows of sample data, then write a basic VLOOKUP for that. If it works, gradually add elements from your original sheet to pinpoint exactly what’s causing the issue.

内容的提问来源于stack exchange，提问作者KingHarambe