I'm sorry to hear that you're experiencing this issue with your Excel formulas. There could be a few reasons why you're getting a zero result, even though you're using the SUM formula correctly.

Here are a few things you can check:

1. Make sure that the cells you're trying to sum are actually numbers. Sometimes, Excel can interpret numbers as text, which can cause issues with formulas. To check this, select the cells you're trying to sum and look at the "Number Format" dropdown in the "Home" tab. If it says "Text", you'll need to change the format to "Number".
2. Check that the cells you're trying to sum are not empty. If there are any blank cells in the range you're trying to sum, Excel will return a zero result.
3. Make sure that the cells you're trying to sum are not hidden. If any of the cells in the range you're trying to sum are hidden, Excel will not include them in the calculation.
4. Check that the formula is actually referencing the correct cells. Sometimes, when you copy and paste a formula, Excel can accidentally change the cell references. Double-check that the formula is referencing the correct cells.
5. Finally, make sure that there are no circular references in your workbook. Circular references occur when a formula refers to itself, which can cause Excel to return incorrect results.

I hope these tips help you resolve the issue with your formulas. Let me know if you have any other questions or if there's anything else I can help you with!