FreeAviator

So i recently got the PMDG 737 800 pack for my FSX but when I install the addon and try to launch FSX, the game shows this: "Product Activation Error: An error occurred while attempting to activate the product. The problem may be due to an incomplete installation of the application. Reinstalling the application may resolve the problem. Otherwise, please contact product support for assistance." What to do to fix this as it isnt even showing where to put the activation code in. Due to this I only get to play 30m of free flight. (Note that the above image is not mine, its a google image but I get the same result too)