<text> attribute x: Expected length

[magnaibayar]

Hello. I'm glad to using Kartograph library.
But i have a issue about adding label symbols.

Here is my code:

.get('Aimag1.svg', function(svg) {
            var div = $('<div />').addClass('mapnail');
            $('#map').append(div);
            var map = kartograph.map(div, w * 0.5, w/3);           
            map.setMap(svg);

            map.addLayer('provinces', {
                styles: {                        
                    'stroke-width': 0.3,                        
                    'fill': "#FFF",
                    'stroke': "#000"                        
                },
                mouseenter: function(d, path) {                        
                    if(path.attr('fill') != 'red')
                        path.attr('fill', '#c04');                        
                },
                mouseleave: function(d, path) {                        
                    if(path.attr('fill') == '#c04')
                        path.animate({ fill: '#fff' }, 1000);
                },                    
                click: function(data, path, event) {                        
                    if(path.attr('fill') != 'red')
                        path.attr('fill', 'red');
                    else path.attr('fill', '#fff');                        
                },
                tooltips: function(d) {
                    return ['/km<sup>2</sup>'];
                }                    
           
               map.addSymbols({
                type: kartograph.Label,                    
                data: map.getLayer('provinces').getPathsData(),
                location: function(d) { 
                //console.log(map.getLayer('provinces').getPathsData()); 
                //return 'provinces.0'; 
                    return 'provinces.' + d.id
                },
                text: function(d) { return d.namemn; }
            });

And the log is: Error: <text> attribute x: Expected length, "NaN".

Thank you for helping!