Problem with Sum function

[jeo]

I have a report where I'm trying to sum up how many days it took to process a task. The report is done each day of the month and if a task was worked on, it gets a 1 (day) for that date.
In my report footer I'm trying to do sum([tbltask]!task1) as a control source and having it do a running sum on All.
When I have this text box in a body of my report, it works fine, but when I put it down in a footer, it says Error#.
Any ideas of what I'm doing wrong?
I tried to do a count and running sum on Group. Neither of combinations work.
Thanks!

 

[jeo]

I got it figured out, thanks anyway.
I needed a report footer, rather than the page footer where I was trying to calculate this.
As soon as I put my calculation on the Report Footer, it worked like a charm.