Hmm ... I never received the OP message, only Wol's reply made it through. :-/
In Kmail make sure you have subscribed on the server folders you want Kmail to
show. Right-click on the top folder and select 'Serverside Subscription' to
show the tree of folders on the server.
To re-index the messages in Akonadi you can right-click on the top folder,
e.g. Inbox, then select 'Folder Properties', 'Maintenance' tab and click the
button "Reindex Folder".
Also, on the Akonadi Console you can restart the 'Akonadi Indexing Agent'.