Silverlight Combobox in DataTemplate open on first click

I've got a combobox in a datatemplate on my grid, I would like to open it on the first click but it seems that the row is selected first. I have tried changing the isDropDown open on rowchange but for some reason it's not working. I have also tried o开发者_如何学Pythonpening the dropdown from PreparingCellForEdit but that was never fired. Any suggestions?

nevermind, I was triggering a datgrid event which called a storyboard from code behind which I am going to assume because of focus or something closed the combobox. Sorry, it wasn't the storyboard but the BusyIndicator that caused the close