Help with Totals

This seems as easy thing, but I just can't get it to work.
In a report, I have a textbox named Miles, which is bound to Miles in a table. I added another textbox with "=sum([Miles])" this is how I thought it was done and I checked the help and this is how it is meant to be done.
When I view the report, however, the text box shows #error instead of the total of the Miles. I have checked to make sure the relevant text box is called Miles and it is, I cannot see why this is happening. Thank you

EDIT: This is Access XP

~Ewan

PS - In case you were wondering, it's called Miles because of the measurement of distance, not the name :).

It's ok, I've sorted it, I was putting the text box in the Page Footer instead of the Report Footer (Mods - Delete this thread please :))
Thanks anyway

~Ewan