How can property division be done if uncle is not willing for division

My mother has a farm land in our home town and the land is shared between our uncle, now we would like sell the property and in order to divide the property into two equal half, the land needs to be survyed for which we need signature/authorization as per the surveyor. We gave the application for land to survyed n uncle agreed at that time. Mom returned to bangalore n now uncle denys to sign the application. The survyor is unable to survey the landland n get the equal half under my morther's name. How do I proceed with this situation?