I'm struggling since a couple of weeks with setting a multiple values cascading lookup field using a client object model, I could set the first value but then It show me an error of invalid lookup value, even I'm sure that the value exist and is valid. I tried different ways but always the same problem. FYI, I could set a simple lookup field even with multiple values but not cascading. I did a lot of searches on the internet and nothing really relevant and helpful at the moment. Any help, I start to loose my mind!!!!!