Data missing when using group-element as opposed to dots

I use this code:

我用这个代码：

svg.selectAll(".dot")
    .data(data)
    .enter().append("circle")
    .attr("class", "dot")
    .attr("r", function(d) { return domainOnlyScale(parseFloat(d.Size)+0.01); } )
    .attr("cx", function(d) {return x(d.x+(Math.random() * 0.25) - 0.125); })
    .attr("cy", function(d) { return y(d.y+(Math.random() * 0.25) - 0.125); })
    .style("fill", function(d) { return color(d.color); })
    .style("stroke-width", "1px")
    .style("stroke", function(d) { return strokecolor(d.color); });
svg.selectAll(".do