Toni,

I think that to get a lock on, the object must be AI. For example I have downloaded a HMS Ark Royal aircraft carrier and when I get a lock on to this ship it is actually the Ai aircraft onboard the ship that I get locked on to, not the boat itself. Not all ships in FSX are true AI models. This is a limitation in this mode.

As for locking on to any other ground targets, I can certainly lock on to ground targets in the form of AI aircraft at airports and also the little fuel truck that runs around some of the supplied airports in the package (Bournmouth airport in the UK for instance, I can target all of the AI aircraft and fuel truck using A to G missiles).

Another way to fire the Kormoran at ships of your choice would be to define them as 'rockets' in the CSWeapon.xml file. In this mode you would select the Kormoran with the selector switch set to 'Rocket' and then fire at will using your assigned trigger. The only downside to this is the missile will explode on contact with the ground/sea and the boat would remain intact. Not all bad though as it means you can swing around for another shot at the same target!
Find this text below in the CSWeapon.xml file and change the word 'MissileLauncher' to read 'RocketLauncher'. Use 'open with' and notepad to edit the file, and dont forget to make a backup first.

<Gun>
           <Type>MissileLauncher</Type>
           <Name>AS-34</Name>
           <Desc>AS-34 Kormoran</Desc>
           <HudString>AS</HudString>
           <Pix />
           <ConeAngle>0.005</ConeAngle>
           <TargetRange>23000</TargetRange>
           <MinRange>2000</MinRange>
           <MaxGForce>3</MaxGForce>
           <Delay>0.0</Delay>

I hope this helps.

Pete