Problem in the Cry of the Warsong scenario

[:1]Hello



In RoC, in the Cry of the Warsong scenario in the Orc campaign, when the quests come up to build a base : a great hall, when i choose the peon, there is no build option, as there is repair, or attack.

I am not able to build the base and progress

I dont know why this is happening, can you tell me how to rectify it.

Thx

SN