Me and my clan have won 2 clan wars in platinum divion. How do we opt in for the daimond division?

After this last clan wars we had won our second clan war in daimond division. But in the cod app we couldnt opt in for daimond division. Are we trying to opt in the wrong way? And could it be that we couldnt opt in for daimond division because our clan leader made someone else with a higher kd the clan leader during the clan war? Please give me some awnsers. Need help. Tried looking for a contact number for support but couldnt find one...