Depending on whether you have Acceleration installed, or not, determines whether you get the FA-18 OR the LX-45. The FA-18 is only available for those with Acceleration, the rest get the LX-45. So....Because you have Acceleration, you get the FA-18. If you can see it, the install is okay. If you can't, which I think is what you are saying, your install is faulty.

If you installation is not working, there are a few things you might need to do.

1) Instal Weapon for FSX "as an administrator". Right mouse click on the Weapon installer (csw001_1000.exe) and select "Run as an administrator" (second from the top, below OPEN) from the box that shows up.
2) Run the Loader as an administrator so that it can make changes to the aircraft that you want to have weapons. Right Click on the "Loader", select properties, select the Compatibility Tab and place a tick (checkmark) in the option to "Run this program as an administrator".
3) You might also need to run FSX as an administrator IF it is installed in the default location (whivh I think is: C:\Program Files (x86)\Microsoft Games\Microsoft Flight Simulator X) so that it will work properly. Right Click on the "fsx.exe", select properties, select the Compatibility Tab and place a tick (checkmark) in the option to "Run this program as an administrator".

If non of that works, just say so and I'll give you a list of more fun things to try. Hopefully that won't be necessary.

Mark