why sometimes my IPAD AIR2 maintain a status of enter passcode even I've entered passcode

Howdy Lovingfish,

If your iPad appears to continue to ask for your passcode then it is rejecting your previous passcode entry and asking you to enter the correct code . If you find that the code you enter is not being accepted you can reset it using the steps in this article -

Forgot passcode for your iPhone, iPad, or iPod touch, or your device is disabled - Apple Support

Thanks for using Apple Support Communities.

Best,

Brett L

Hi Lovingfish,

Thank you for using Apple Support Communities. Due to the nature of the issue you described you may find more information by using another one of Apple's support resources - https://getsupport.apple.com/GetproductgroupList.action.

Brett L