jqGrid: set a color conditional custom formatter b

Question

I've seen other posts on this subject but my is slightlty different I have a jqGrid as shown below with the following name:

 grid = $("#list");

Now, I have a column named total and I want to set a color for the numbers based on a value. I tried like this

grid.jqGrid({
...
colModel:[
...
{name:'total',index:'total',width:60,
    formatter:function(cellvalue, options, rowObject){
              if (cellvalue > 300) {
              return "<span style='background-color:orange'>"+cellvalue+"</span>";
              } else {
              return "<span style='color:red'>"+cellvalue+"</span>";
              }
              },

                  align:'right'},
...

which seems to evaluate fine the if conditional but fail to display the cellvalue variable.

How should I redisplay the total cell value with the proper markup inside the if brackets?