Correct and incorrect feedback location

I am doing a Go\no go taks. After a correct response I am giving the participants a Green "O" feedback on the same screen. However, after the incorrect response I am giving them a Red "X" on new screen. This method I have adopted from ...\DirectRT\samples\6 v2008\gnat.
Now I want the X also to appear on the same screen if their responses are wrong.
I tried using the trial<-999 without clearing the previous screen but this is still not working. I am still getting the X on a new screen.
Please suggest how to resolve this problem.

In the original sample, don't the X and O both appear on the same screen as the stimulus?