Sharepoint 2013 .NET CSOM CamlQuery Join

I am unable to create a working query with join in my .net csom application. I was using this article:

http://msdn.microsoft.com/en-us/library/ff798388.aspx

here is my code:

 ClientContext context = new ClientContext(url);
 Web web = context.Web;
 var list = web.Lists.GetByTitle("Esemény");

 CamlQuery cq = new CamlQuery();
 cq.ViewXml= @"<View>
                   <ViewFields>
                       <FieldRef Name='Title' />
                   </ViewFields>
                   <ProjectedFields>
                       <Field Name='PartnerLookupTitle' Type='Lookup' List='PartnerLookup' ShowField='Title' />
                   </ProjectedFields>
                   <Joins>
                       <Join Type='LEFT' ListAlias='PartnerLookup'>
                           <Eq>
                               <FieldRef Name='Partner' RefType='ID' />
                               <FieldRef List='Partner' Name='ID' />
                           </Eq>
                       </Join>
                   </Joins>
               </View>";

ListItemCollection lista =  list.GetItems(cq);
context.Load(lista);
context.ExecuteQuery();

I get an exception from the server: "Value does not fall within the expected range."

If I remove the the ProjectedFields and Joins part of the CAML query it works:(

Ok. I could create a working query:

                @"<View>

                    <ViewFields>
                      <FieldRef Name='Title' />
                      <FieldRef Name='Partner'/>
                      <FieldRef Name='PartnerLookupTitle'/> //new code
                    </ViewFields>

                    <ProjectedFields>
                        <Field Name='PartnerLookupTitle' Type='Lookup' List='PartnerLookup' ShowField='Title' />
                    </ProjectedFields>
                    <Joins>
                      <Join Type='LEFT' ListAlias='PartnerLookup'>
                        <Eq>
                          <FieldRef Name='Partner' RefType='ID' />
                          <FieldRef List='PartnerLookup' Name='ID' />
                        </Eq>
                      </Join>
                    </Joins>

                  </View>";

Now I can acces the PartnerLookupTitle field, but still dont get this line of code:

<FieldRef List='PartnerLookup' Name='ID' />