The syntaxe should be something like : =Sum(Fields.Item("Something").Value)
Where "Something" is the field that you want to sum.
The easiest way to edit a field value whith an expression, is with the Expression Editor.
Select the field you want to fill and in the field parameter, select Value > Expression ...
Here a screenshot, with a example
Could have sworn that I tried that format...using the Report Designer editor to build it...
I did notice that in the table view it shows up as Sum ( [Other] ) even though I enter it in the properties as =Sum( Fields!Other.Value ), maybe that is where I went wrong, entering it in the properties as Sum( [Otrher] ) ?
Thanks for the reply!