You use the word "expand". Does that mean it was already a castle? I would guess it was a fortification. In that case you need 2 Talentpoints to expand it by 1. 9/2 maks 4, so all would be OK.

That's it... duh! Sorry.

Actually... according to the english rules, it's harder to enlarge the castle, but it should still have enlarged it by 9:

"The table below shows when a castle reaches a new size category. In general, one can say the larger the castle, the more difficult it is to enlarge. To enlarge a castle, the given minimum skill level in masonry must be met. Then one can stone can added to a castle for each person and each skill level per unit. A highly skilled unit with enough stones is able to construct a tower in one round."

But I guess in the german rules it says it differently... Not a bug, just wrong in the english manual. I'll have to change the wording there.

sounds to me this was a matter of the rules, not the code? then I'll close this.