No Objection certificate (NOC) in PSU service

I have a peculiar problem and need help urgently to bring my career back on track. It goes like this: I was working in a Central PSU. I resigned from there and got my relieving letter as per rules. I joined another Central PSU nearer to my hometown. While joining in this new job I could not produce NOC from my previous employer, so I joined as a fresh candidate without pay protection. Now when I try to apply to any other PSU job I cannot show my past experience since my current company will not recognise my past experience. Hence I am missing out several good opportunities. How can I regularise my past experience in this company? If so, can there be any problem with regard to vigilance?