You need to be in one clan....
Not One for XBL and One for PSN
Merge the two together into one.
I believe as leader you need to have an account on both systems or you will not see the ops for the other platform.
My clan is XBL only... Anyone out there have a cross platform clan willing to share insight?
ps OP I would change the title of your post to "Cross Platform Clan - Share Elite Clan Tag?"