Is it possible to add multiple GroupByExpressions programatically (C#)?

I tried:

GridGroupByExpression expression = GridGroupByExpression.Parse("fld1, COUNT(fld1) Total GROUP BY fld1");
RadGrid1.MasterTableView.GroupByExpressions.Add(expression);

GridGroupByExpression expression2 = GridGroupByExpression.Parse("fld2,, SUM(fld2) Total GROUP BY fld2");
RadGrid1.MasterTableView.GroupByExpressions.Add(expression2);

And it appears that only the second expression applies, resulting in a grid with only one level.  Editing the ASPX direclty, as shown in the previous post, results in two levels, at least proving that my data is valid.

Thanks!

I have written the same code but this is not working for Sum Aggregate function.In the gridgroupheaderitem the header text is not generating the sum of the values of the specified column---

Code:
GridGroupByExpression expression = new GridGroupByExpression(); 

GridGroupByField gridGroupByField = new GridGroupByField(); 

//GroupByFields values (group data) 
gridGroupByField = new GridGroupByField(); 
gridGroupByField.FieldName = "EmployeeID"; 
expression.GroupByFields.Add( gridGroupByField ); 

// SelectFields values (appear in header) 
gridGroupByField = new GridGroupByField(); 
gridGroupByField.FieldName = "EmployeeID"; 
gridGroupByField.HeaderText = "Employee"; 
gridGroupByField.HeaderValueSeparator = " for current group: "; 
gridGroupByField.FormatString = "<strong>{0}</strong>"; 
expression.SelectFields.Add( gridGroupByField ); 

gridGroupByField = new GridGroupByField(); 
gridGroupByField.FieldName = "Freight"; 
gridGroupByField.HeaderText = "Total shipping cost is "; 
gridGroupByField.HeaderValueSeparator = ""; 
gridGroupByField.FormatString = "<strong>{0:0.00}</strong>"; 
gridGroupByField.Aggregate = GridAggregateFunction.Sum; 
expression.SelectFields.Add( gridGroupByField ); 

tableViewOrders.GroupByExpressions.Add( expression ); 

Can anyone help...??