When does flex throw NetConnection.Call.Badversion Error

I am using Flex as my client and Java as my server. Using WebOrb in remote host. At times I recieve this error.

faultCode:Client.Error.MessageSend
faultString:'Send failed'
faultDetail:'Channel.Connect.Failed error NetConnection.Call.BadVersion: :
url: 'http://foo.com:5480/bar/weborb.wo''

I don't know why this comes. I googled for it and found no answer. Everything works fine if I handle it in fault handler. But I want to know why this comes. What should I do to avoid this error.

Any help would be greatly appreciated.

Thanks for the response..

Here is my abstracted code

public class FOOProxy implements IFOOProxy
{
    public static var FOO_PROXY:IFOOProxy;
    private var remote:RemoteObject;        

    public function FOOProxy()
    {

    }

    public function runCommand(request:IClientRequest):void
    {

        remote.addEventListener("result", onResult);
        remote.addEventListener("fault", onFault);          

      if(request is GeneralRequest)
        {
            var req:Request = request as CmdRequest ;
             if (req.requestType == fooController.UPDATE_REQUEST)
             {
                remote.requestTimeout=null;
             }else
             {
                remote.requestTimeout = 30;
             }                  
         }      
        remote.runCommand(request);

    }

    public function onResult(event:ResultEvent):void {
        var result:Object = (event as ResultEvent).result as Object ;
        /*
        Updating my result using callback.
        */
        CursorManager.removeBusyCursor();
    }

    public function onFault(event:FaultEvent):void {
        if(event.fault.faultCode=="Client.Error.MessageSend")
        {
            //This is where "NetConnection.call.badversion occurs"
        }

        else if(event.fault.faultCode=="Server Exception")
        // Server Exception Handling
        {               
                //Dispatch Something
        }           

    }



    public static function createProxy(callback:ICallback):IFOOProxy {
        if (FOO_PROXY != null) {
            FOO_PROXY.setCallback(callback);
            return FOO_PROXY;        
        }
        var iProxy:IFOOProxy = new FOOProxy();
        var proxy:FOOProxy = iProxy as FOOProxy; 
      //setting my callback here to update
        proxy.remote = new RemoteObject();
        proxy.remote.destination = "Rpc";           
        return proxy;
    }

}

This is where it connects with server-: Destination id "Rpc"

I am using https, port number 5480 and using secure-amf as channel in remote -config.xml

Thanks in advance.

The badversion error often is the result of the web server showing an error when doing the remote call instead of throwing the exception amf-style. Since the amf client can not parse the response you get that error message.