I assume you checked to see that nothing fell behind the slide before you extended it? We've had a few things fall behind, like a tv remote, books etc...
2007 Dodge Ram 3500 Cummins SRW, Airlift airbags, Bilstein shocks, Smarty Jr., stainless turbo back exhaust, B&W Patriot 18K
2015 Grand Design Momentum 328M, disc brakes, Progressive Industries 50 amp EMS