jQuery Grid Plugin – jqGrid

I'm just trying out the "addRowData" method in jqGrid 4.3.2 for the first time to see if I can asynchronously load row data from multiple sources.

To start with, I load a table with some data the "normal" way (not using addRowData()) to verify that everything is working, and everything works.

When I then try to add a new row (e.g. using one of the rows from the initial working result):

var new_row = [{"time":{"end":"20120507235959","start":"20120507000000"}];

$("#grid").jqGrid('addRowData', 0, new_row)

Where time.start and time.end are defined in colModel as:

            {name: 'timestart', index: 'time.start', jsonmap: 'time.start', formatter: self._formatters.date, width: 145, fixed: true},
            {name: 'timeend',   index: 'time.end', jsonmap: 'time.end', formatter: self._formatters.date, width: 145, fixed: true}

Then I get the "TypeError: value is undefined" error. It seems that the time field is not being passed properly to the formatter. The other fields (options and row) are set correctly, just the "value" field is undefined.

Any ideas?

Thanks,

Keith