How to push function with custom parameter into $.fn.dataTableExt.afnFiltering?

My table has 2 rows in the table header. The first row contains th elements that may or may not contain a select element. I want to push filter functions into $.fn.dataTableExt.afnFiltering but specify the column index of the column being filtered. I am using the code shown below. Notice I am passing the col parameter to the filter function. The alert never gets called. How can I make this work?

var initializeFiltering = function ($this, settings) {
            
        var filter = function (oSettings, aData, iDataIndex, col) {

            if (col > 0) {
                alert("!");
            }

            if (settings.$reportDataTable == undefined ||
                oSettings.nTable != settings.$reportDataTable[0]) {
                return true;
            }

            switch (settings.filters[col].value) {
                case "*":
                    return true;
                default:
                    return oSettings.aoData[iDataIndex]._aData[col] == settings.filters[col].value; //// CAUTION INDICIES
            }

            return true;

        };

        settings.filters = [];
           
        $("#ReportDataTable").find("tr.filters").find("th").each(function (index, ui) {

            settings.filters.push({});

            $.fn.dataTableExt.afnFiltering.push(function (oSettings, aData, iDataIndex) {

                filter(oSettings, aData, iDataIndex, index);

            });

        });

};

Thanks!

Robert