=IFERROR() "value_if_error" incongruity

[Monster Island]

Hello there. New poster here, so I'm nearly guaranteed to pose an already-asked question, I suppose. I did search for it though!

I'm using Excel 2007 with Windows XP Professional Ver 2002 SP3.

Here's a basic version of a table I'm working with.

[TABLE="width: 200"]
<tbody>[TR]
[TD]M[/TD]
[TD]M[/TD]
[TD]M[/TD]
[TD]M[/TD]
[TD]M[/TD]
[TD]SM[/TD]
[/TR]
[TR]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]C[/TD]
[TD]C[/TD]
[TD]C[/TD]
[TD]C[/TD]
[TD]C[/TD]
[TD]SC[/TD]
[/TR]
[TR]
[TD]5[/TD]
[TD]7[/TD]
[TD]8[/TD]
[TD]10[/TD]
[TD]11[/TD]
[TD][/TD]
[/TR]
[TR]
[TD]1[/TD]
[TD]2[/TD]
[TD]3[/TD]
[TD]4[/TD]
[TD]5[/TD]
[TD][/TD]
[/TR]
[TR]
[TD]10[/TD]
[TD]12[/TD]
[TD]14[/TD]
[TD]15[/TD]
[TD]14[/TD]
[TD][/TD]
[/TR]
</tbody>[/TABLE]

So I have a table like the one above. I'm doing a COUNTA for the columns - each one represents a day - as =COUNTA(A4:A6) where you see each "C". This is intended as a quantity of cells that contain values.

Elsewhere, I have another section of the table which does another calculation of minutes spent on that particular day, which are listed where you see "M". For the sake of this formula, it doesn't matter what's in here.

"SC" is a sum of "C" values. This formula is =IFERROR(SUM(C1:C5),"----"). In my current table, this returns "0".
"SM" is a sum of "M" values. This formula is =IFERROR(SUM(A1:A5),"----"). In my current table, this also returns "0".
Elsewhere, I have the following formula: =IFERROR((SC*60/SM),"----"). This returns "----".

Why do the first two circumstances of =IFERROR return "0" while the third returns "----"?

I also welcome any input if my method seems foolish. Hopefully this is clear enough!

Thanks!

-MI

 

[Andrew Poulsom]

Yes, that's right.