Agreement is made but land not register

hii all,  I purchased a land nearly 10 years ago from seller and agreement is also  made  in 100 Rs stamp. ie seller sells is land.and all the rights belongs to us and  no specific time is also not mentioned about registeration and seller also sign in the agreement. but now is refuses to register the land. Can we take any action against the seller and how can we acquire that land?? Agreement can  we treat as edivence to register a land with out seller