Validity of MOH Viva.

Hi dear Forum members,
I am a BSc Nurse specialized in IVF. I am from India and I have 5 years of experience in the field. I Cleared my prometric exam for Oman and I got an offer from a Hospital in Muscat. I visited Oman on Visit visa since my husband is working in Muscat; and I attended the MOH Viva through the referral of the hospital and passed the exam in 8th Feb 2015.
I went back to India as per the instruction of the hospital officials and send them my medical from GAMCA approved clinic from India. It has been almost 10 months since then they have not provided me the job visa. I tried to get NOC from them many times they were not ready for that also. Now they are saying that they cannot provide me the earlier agreed Job thus shall give NOC in a week or so.

When I approached another hospital for job they are doubtful about the validity of the MOH viva exam result.

Does anybody here can tell me about the validity of MOH Viva test? Is it 1 year or 6 months? I passed the Viva on 8th  Feb 2015

Where / How  I can verify the validity of My MOH viva exam?

Please, somebody help.

Thanks