How can I resolve iMessage passcode verification issues on iPhone?

when im activating my phone for imessage and it asks for my ipads passcode i put in my ipads passcode and yet it still says its incorrect. im unable to use messages on my phone because of this i need help asap (i have to put it my iphones passcode first then it gets to that and no matter what it just doesnt work, i even tried changing it because i used the same passcode and it was saying to not use the passcode of this device so i changed it and its still saying its wrong.)

[Re-Titled by Moderator]

Original Title: correct passcode being incorrect for verifying to use imessage.