Sumif help very confused!!!

you could apply a filter to column A and see if some other values match what is in A109. If you apply the filter you should see which other cells match that value so you could see which cells in col E were summed. You could also do a countif against A109 in column A to see how many there are.

You referenced an entire million-row range...and you want Excel to show you every value...in the formula bar. Did I get that right?
Also, A109 is within the test range (Col_A), which may cause problems.

Try this instead...to test your formula
• Run your formula down a blank column, referencing only the cells in one row
Example:
=SUMIF(A2,$A$109,E2)
• Copy that formula down as far as your data goes.
Now you can see every row that matches the criteria and the value that will be summed by the original formula

Beyond that...
Never reference an entire column.
If possible, convert your data range to an Excel Table. Then, by using structured table references, the formula references will expand/contract to accommodate the actual data.

Does that help?