why can't I unlock my samsung tab 4. password doesn't work

[AC Question]

Using Android device manager on my samsung phone I locked my tab as a test. Now I can't unlock. The message tells me incorrect password. I read if I lock the device again I will be asked for another password that be now the correct password. I did this several times and still cannot unlock my tablet. It doesn't accept any new password as well. I'm sure this must be a common problem with the ADM.