Chat history between windows and ios

Hi so here is the current setup

Server is Skype for business 2015 on premise

and the email is O365

So if i log in on SFB on PC and start a chat with someone, when i go on my IOS APP the chat is not there it's like it never happened

Same if i chat on my IOS on PC it shows as it never happened

I actived the Conversation history in outlook but it doesn't show in the APP

Can i get some assistance please