Rotate orbit camera

I've setup the orbit camera as follows:

LocalClientConnection.camera.setOrbitMode( $Towers::selectedObject, $Towers::selectedObject.getTransform(), 2, 20, 10, 0);

But how do I then rotate the camera about this object? I've tried the following but it doesn't work:

$myRotValue = $myRotValue + 0.1;
%pos = getWords($Towers::selectedObject.getTransform(), 0, 2);
%rot = " 0 0 1 " @ $myRotValue;
%trans = %pos @ %rot;

LocalClientConnection.camera.setOrbitMode( $Towers::selectedObject, %trans, 2, 20, 10, 0);

Thanks in advance.