Ipad Mini 4 WIFI only problem

I have Ipad Mini4 (wifi only). I update official update ios11, its worked a while, and then touchid stopped working.I sign out of my applied account and chose ERASE ALL CONTENT AND SETTINGS. When ipad boot up I choose language,region and wifi, insert my wifi passcode and get information “I pad could not be activated because the activation server cannot be reached etc…” I tried several times past days. I connected my Ipad on Itunes and got message “The Ipad could not be activated because the activation information could not be obtained from device. Disconnect your Ipad, make sure the SIM is inserted correctly and, if you use SIM PIN, tap Unlock to enter it, and then reconnect you iPad”.Everything is updated, itunes everything.

Why this happens?My ipad is Ipad Mini 4 WIFI ONLY, why itunes cant recognize device, why always ask me about SIM? Please help me.