TreeGrid Footer

Hi,
firstly sorry if there is a similar post somewhere else. I have a purchased version of dhtmlx. I am not sure how you attach a footer with a total sum of a particalur column into a grid. I have had a look at the doc and do not quite understand them. I only have this bit of code so far

mygrid.attachFooter(",

,#stat_total");

but not sure what to do next, any help would be great.
D

Please read this tutorial http://docs.dhtmlx.com/doku.php?id=dhtmlxgrid:math_in_grid#automatically_calculated_values_for_header_footer

And look at this sample in addition http://www.dhtmlx.com/docs/products/dhtmlxTreeGrid/samples/04_grid_operations/01_treegrid_aggregation.html

And for sure your code must include the dhtmlxgrid_filter.js extension.