I had to do a reinstall of windows 8.1 and FSXSE and all updates etc. I downloaded the latest Add-on Manager program 3005. When I go to install the serial number, it asks me if I have it and to enter it in the next window. That window never opens. I tried it in full screen and window mode. Also tried the button to register serial number, no luck. I also updaded Couatl from the check live update button just in case. I also tried to uninstall and reinstall, no luck.