I've got Hearthfire, I've got the houses in falkreath and morthol but i cant get the house in Dawnstar is there something wrong with the DLC? i've read some other problems online with this.
Go to the Inn and talk to Erandur the priest and do the quest with him. I think you also have to do a quest for the Jarl about killing a giant. You won't get that quest until level 22.