Provision House Upgrade

[stonewaller]

I know I'm not alone in this, so is there a link out there which I can't find....
My lvl 4 Provision House has greyed out upgrade arrows, so I cant get it to level 5.... anyone know why?

[minion79]

the mostly likely reason is that you don't have the resources for the upgrade to level 5.

If this isn't the case a screenshot would possibly help find the cause.