jQuery Grid Plugin - jqGrid

In the definition of the top grid I have the following:

gridComplete: function() {
    if(dns_expand_id) {
        //alert(dns_expand_id);
        $('#dns').expandSubGridRow(dns_expand_id);
        dns_expand_id = null;
    }

},

dns_expand_id is initially null.  I need certain events in the subgrid to trigger a reload of the grid and want to expand the subgrid that triggered the reload.  So, after a successful server request I set dns_expand_id to the rowid containing the open subgrid and call

$('#dns').trigger('reloadGrid');

I know from the alert() that the correct value is passed to expandSubGridRow() but it isn't expanding and no errors are generated.

Any ideas on what I'm doing wrong or where I might look?