I have a question that my thread just approved and I played this game in some sever  its quite fluently but today I can not join again ,these severs said:'you are banned from bf4db ' and kick me out , that made me so confused ,then I check my bf4db there is no ban on me, how can I do ?

It's a ban from server admin, not us, you need to speak with them and show them that you are not banned by us anymore.