Please could you help me or offer advice on how I can resolve the following problems on Gears of War 3:
* i have the 'I got this' achievement, but it didnt unlock the ivory weopon skin.
* I have completed campaign on 4 player + have the achievement, but it didnt unlock the friendly fire mutator.
Any feedback would be much appreciated. Is there anyway that these can be unlocked or will i never be able toi get them?