Decree Not Executed

Thanks for your help in advance! The district court passed a decree providing the claim to my land in 1995. I filed for its execution and then also for permanent injunction. case was against my father's brother. (Land was owned by my father & his brothers and my grandfather's brother's sons) The defending party, in the meanwhile sold the land to property dealers. Now property dealers have registery but their names aren't on the revenue records. Recently, the execution was rejected by the revenue officer citing the reasons that co-sharers(property dealers) weren't made parties to the case. My question is Can they actually challenge the decree after so many years (more than 12 years)? The land in 1975 was on the name of the same party, i filed a suit in 1985 and won it in 1995. Then co-sharers never made claim. can they do it now? Also can i appeal for mandamus in high court, asking government officers to do their job(execute the decree)? As i am pretty sure bribe is involved. Thanks