why is "sum" displaying zero?

[Rough Trade]

When I select a range of numbers to sum the result is zero. The formula is
shown in the formula window and I am using the auto sum feature so I am not
creating a syntax error.

 

[Max]

When I select a range of numbers to sum
the result is zero. The formula is
shown in the formula window
and I am using the auto sum feature so I am not
creating a syntax error.

One guess is that the numbers are probably text

Select an empty cell,
clear it with the Delete key, then copy it

Then select & right-click on the range of "numbers"
Choose Paste special > check "Add" > OK

The SUM(...) should work now.

 

[Max]

Select an empty cell,

clear it with the Delete key, then copy it

The bit: > clear it with the Delete key
is to ensure that the cell's really empty