What event should I use to grab the record count of a DataGrid?

Question

I have a "Go" button on a search form.  It works correctly, fetching records from a CF data service into a data bound DataGrid.  However, using the code shown below, the record count always shows zero.  I've tried putting the "..Provider.length" line shown below, into various events on the grid, so that it will always update the count at the correct time, but I get "null" object errors at run time. There seems to be no event that fires "AfterDataLoad".
            protected function btnGo_clickHandler(event:MouseEvent):void
                 getSBJsResult.token = baa_data_svc.getSBJs(cmbSrch.text);
                 tabSbjs.label = 'Subjects: ' + grdSBJs.dataProvider.length;    //  This always returns zero.  Why?

Answer 1

For example, this doesn't work.  The grid is told to loaded data on line 1, but this must just be only a message send to the Flash Player 10, because the processing doesn't stop and wait for the loading of data to complete, it just continues on to line 2, at which point '...Provider.length' is always zero the first time through.   So... the NEXT time the user clicks the Go button, line 2 is processed for the DataGrid which is holding data from the PREVIOUS search, so it updates the tabSbjs.label with the count from the previous search, not the current search.  The count of records is always for the previous data set.
            protected function btnGo_clickHandler(event:MouseEvent):void
1               getSBJsResult.token = baa_data_svc.getSBJs(cmbSrch.text);  // edtSrch.text
2               tabSbjs.label = 'Subjects: ' + grdSBJs.dataProvider.length;                                                                            
All I'm trying to do is (which seems like a very difficult thing to do in FB4):
-Display a DataGrid popluated with data records
-Display a count of how many records are in the data grid
If I rely on CF9 functions, which can only return a single value, then I have to make two CF9  functions, with the exact same SQL, one that returns data, and one that returns a count of the records.... which is non-sensicle.
There must be a simple way to do this, but I'm going around in circles.