I'd expect you could easily rule-out the CommandArgs as being the cause of the problem by simply running a test without them. :)
That said, CommandArgs shouldn't be causing this issue. I expect it's related to some other configuration on your page. If you're still struggling with this problem, please post the full markup for your RadGrid. That will help reveal if everything appears to be configured correctly.
I'd also suggest posting questions about RadGrid in the RadGrid forums in the future for a much faster response. The "General Discusssions" threads don't get the same product attention as the product specific forums.
Let me know if I can provide more help.