I did not read your situation clearly writing my previous answer.
So you are in OPT, I assume you graduated from this university in 2002 or 2003.
So the question is, how did you got accepted to a program without ISO's knowledge? Did you not apply? and when you apply, did you not check on the application form that you need student visa sponsorship? If you did all those things, when department accepted you as a new/transfer student, ISO would have stepped in and issue you I-20 before you can register.
So you are in OPT, I assume you graduated from this university in 2002 or 2003.
So the question is, how did you got accepted to a program without ISO's knowledge? Did you not apply? and when you apply, did you not check on the application form that you need student visa sponsorship? If you did all those things, when department accepted you as a new/transfer student, ISO would have stepped in and issue you I-20 before you can register.