I'm not exactly sure about your situation, and Freddie (Hotkeynet) or olipics may be able to help you better, but I'm guessing you're sending the actual mouse click to the slave window. I do the same thing for casting my treants and it doesn't have 100% success rate, due to delays or other issues. However, for mouseover healing instead of sending the mouse click I send the mouse position and a key press (for example shift-f). This seems to be very reliable... it may have something to do with the actual mouse clicking needing to take the program delays into consideration whereas the button press is quicker. Who knows