[jQuery] Tablesorter, problems ordering numbers

[jQuery] Tablesorter, problems ordering numbers

Hello,
I have a tablesorter with a numeric column (the type is String so I have to use a parser to order the column as number ), the problem is that it does not order long numbers with comas separator.
Here is the example of the sorted column:
desc order-->  -363,122,000.00; 
                      -28,000.00;
                       3,364,000.00;
                      10,000.00;
                       68,000.00
asc order--> 68,000.00;
                  10,000.00;
                  3,364,000.00;
                  -28,000.00;
                  -363,122,000.00
And this is part of my code:
$.tablesorter.addParser({
        id: "digit2",
        is: function(s,table) {
            var c = table.config;
            return $.tablesorter.isDigit(s,c);
        },
        format: function(s) {
            alert(s);
               if (s.match(',')) {
                    s = s.replace(/\,/, '');
               }
               if (s.match('<')) {
                    s = s.replace(/\</, '');
               }
               if (s.match(' ')) {
                    s = s.replace(/\ /, '');
               }
            return $.tablesorter.formatFloat(s);
        },
        type: "numeric"
    })
   
        $("#credits").tablesorter({headers:
                {0:{sorter:'text'}, 1:{sorter:'text'}, 2:{sorter:'text'},
                 3:{sorter:'digit2'}, 4:{sorter:'digit2'}, 5:{sorter:'digit2'},
                 6:{sorter: 'dateYYYY/MM/DD'}, 7: {sorter:'digit2'}}});
Can anybody help me with this??
Thanks a lot!!
Sole