My son selected by MOH Singapore for job of Medical Officer

Hi my son Dr. Abhishek Kumar was selected by MOH Singapore for job of Medical Officer. He received all the mails for selection, offer letter, posting place with department & departure dates etc. Only few day before departure we received a mail that my application is rejected on the basis of FIN which tells that I had applied previously from another Employer at Singapore. Truly speaking I have not applied in Singapore job previously. There may be clerical mistake or reason best known to them. My whole carrier is at stack. Kindly suggest what should I do? Dr. Kalika Sharan Singh, father of the candidate.

An EP application is never rejected because the father applied for an EP before. You got wrong information here!
Even if you were a serious (i.e. criminal) offender of immigration or other laws, it is unlikely your son gets punished for it.
I also don't understand why your career is endangered because your son cannot find a job. Maybe you meant something else?
The employer can try to find out the real reason for rejection from MoM. If there is really some mix-up (although clerical mistakes are very rare in Singapore), it can be solved easily.