Can promotion be given when employee is on Lien and serving another department

I was working in a govt. organisation for the past 23 years. Thereafter, I was granted 2 years Lien and I joined another department to a higher position. In my previous organisation, my assessment was due for the last two years. Once I joined new position, my old organisation asked to submit the report for assessment purpose and I did the same. The assessment committee considered my case and recommended for promotion but the old organisation withhold my result and is not giving me my promotional benefits by stating that I have left the organisation. I have following points in my favour: 1. My GPF, pension contribution etc. is being monthly sent to old organisation, therefore, I have not left the services of old organisation. 2. My present position is tenure based and not on the basis of absorption. 3. On the due date of promotion, I was in service at old organisation. If my assessment had taken place on time, I would have got my promotion benefits. 4. If I was not on the rolls old organisation, why my assessment was considered and put up before the assessment committee. From the date of start of assessment process to the declaration of result, the situation has not changed. 5. I also know one case wherein one candidate was considered and his promotional benefits were given when he was on lien. If he can be given promotional benefits, I should also be given on similar grounds. please suggest me, if I should approach CAT.