@country_boy : There was no gap in employment. They denied with a reason that I didn't attend the class while I was in F1. I applied for one of the university for master after OPT ended and transfer the SEVIS. Later that university transfer my SEVIS back to prior university from where I graduated. They terminated SEVIS with not attending to class. Now, I485 is denied based on violation of non-immigrant status (F1).

@Mr p: My lawer said that I should file 601 but looks like is not possible in this case. I am still awatiing for other advice.