I am working on an assembly for one of the company owners pet projects that has a part with a linear slide mated to it. The linear slide and carriage I modeled as 2 parts and brought them together as their own assembly. This assembly allows the motion that I want and says that it is fully defined, however when I am in the top level assembly (linear slide assembly mated to its support beam) the carriage won't move. When I click on it and try to drag it, it only allows me to select individual faces or facets of the slider part and it stays frozen in space. I've attached the assembly file. Can someone please tell me what I'm missing?

Thanks

Peter-

The file is SW2009sp4