CF9.0.1 and Flex4 Remoting Issue

We are trying to migrate our flex apps from CF8.0.1 to CF9.0.1 and we are getting an error that seems to be caused when trying to create a VO which is typed to a CFC that is in a directory below the webroot. This was working in CF8.0.1.

The UserVO.as has the following RemoteClass Attribute:

[RemoteClass(alias="flex.coms.CF9Testing.UserVO"")]

public class UserVO

This maps to a CFC with the following attributes:

<cfcomponent access="remote" output="false" alias="flex.coms.CF9Testing.UserVO">

The properties all bind correctly and the path is correct, but as soon as we try to pass an object from Flex to CFC we get the following error in the logs.

[BlazeDS]Cannot create class of type flex.coms.CF9Testing.UserVO'.

flex.messaging.MessageException: Cannot create class of type 'flex.coms.CF9Testing.UserVO'. Type 'flex.coms.CF9Testing.UserVO' not found.

If we remove the mappings and put a copy of the VO in the webroot, it works fine.

Can any one shed any light on what we are doing wrong?

Thanks,

Mark