What do you mean by "it failed"? Is this giving you an error? 

When you say "the default row selector is nothing", what do you mean? Does this mean you don't want the row selectors to show up at all? If thta's the case, then the line of code you have here is correct. If it's not workiing, then something else must be happening after that line of code to turn the row selectors back on. Perhaps you should move that code into the InitializeLayout event of the grid.