what error message are you getting?How are you trying to accept the invite? Go to clan wars page on Ghost ap, click on box with 3 horizontal lines, drop down should give you option of Diamond Division invite, click on it and follow directions. Hope that helps.... post up and let us know if you get in.
The app has been doing some crazy things thsee past couple of days. There are no clan wars this week so you still have time for the app to try and straighten itself out. After that then KC_KREW gave directions on how to accept the invite aftet the app is back up for you.