Makes sense :)  thanks, My dornish Kingdom shall carry on its snail pace advance !

Yeah im pretty sure you need to own the whole county. I never liked how upgrades work in the mod.

I Didn't own the county capital, no. weirdly though i took the county capital and gave the lord my "faulty" castle... low and behold about 6 months later i could send my castellan to this lords castle to improve it.. 

Do you own the county or did you just build a barony?

Im ruling Dorne and built a new castle in spottswood, i have told it to improve castle and even had a message saying i should assign my castellan but when i click for him to do it no highlighted area come up ? im i doing something wrong or is it a bug. 

Cannot Assign castellan to improve holding ?