GPT-5.6 Luna vs GPT-5.6 Sol for spreadsheets & Excel

The fault is in the `VLOOKUP`:

- `Sheet2!A:D` contains **four columns**, but the formula requests column **5**.
- If the intended return column is D, the column index must be `4`.
- The value returned by `VLOOKUP` must also be numeric because it is being added to the `SUMIF` result. If column D contains text, convert it to a number or correct the source data.

Assuming the lookup value is in column A and the desired result is in column D, use:

```excel
=SUMIF(A:A,">"&TODAY()-30,B:B)+VLOOKUP(C1,Sheet2!A:D,4,FALSE)
```

If you actually intended…

**Fault:** `VLOOKUP` requests column **5**, but `Sheet2!A:D` contains only **4 columns**. This normally produces `#REF!`, not `#VALUE!`.

Assuming the intended return column is **D**, use:

```excel
=SUMIF(A:A,">"&(TODAY()-30),B:B)+VLOOKUP(C1,Sheet2!A:D,4,FALSE)
```

The original `SUMIF` criterion is valid; the added parentheses simply make the date calculation explicit. If a fifth return column is actually required, the lookup range must extend to column E instead:

```excel
=SUMIF(A:A,">"&(TODAY()-30),B:B)+VLOOKUP(C1,Sheet2!A:E,5,FALSE)
```