Well, as for as i know the deputation is a game of REFERENCE cuz only those people usually get depution who are well-connected in secretariat. Otherwise, the dep. that need some staff on urgent basis, circulate a letter seeking the willingness of officials/officers and then the process start. But most dep. try their best that their staff could not have knowledge of these posts and they dont circulate this letter.
I suggest u to apply for another job, if you are not happy at present job, instead of seeking deputation.