I have coded in a building tree with more than one upgrade and have had it work fine. But I'm trying to make a tree that up grades different buildings for different factions. The code looks like this;

Code:
building taverns
{
    levels tavern tavern_faction1 tavern_faction2 tavern_faction3 tavern_faction4 
    {
        tavern requires factions { pontus, dacia, egypt, armenia, numidia, } 
        {
            capability
            {
            }
            construction  1 
            cost  200
            settlement_min village
            upgrades
            {
                tavern_faction1
                tavern_faction2
                tavern_faction3
                tavern_faction4
            }
        }
        tavern_faction1 requires factions { pontus, dacia, } 
        {
            capability
            {
            }
            construction  2 
            cost  800 
            settlement_min town
            upgrades
            {
            }
        }
        tavern_faction2 requires factions { egypt, } 
        {
            capability
            {
            }
            construction  2 
            cost  800 
            settlement_min town
            upgrades
            {
            }
        }
        tavern_faction3 requires factions { armenia, } 
        {
            capability
            {
            }
            construction  2 
            cost  800 
            settlement_min town
            upgrades
            {
            }
        }
        tavern_faction4 requires factions { numidia, } 
        {
            capability
            {
            }
            construction  2 
            cost  800 
            settlement_min town
            upgrades
            {
            }
        }
    }
    plugins 
    {
    }
}
I can build the tavern but I don't get the option to build any of the factional upgrades. What am I doing wrong or overlooking? Any help would be appreciated.