I\'ve been trying to figure out the difference between RenderAction and Action. I don\'t know if I\'m so concerned about the differences at this point, as to why I can\'t ge
Try:
@{Html.RenderAction("Breadcrumb", "Navigation", new {SeoUrl = Model.CarlineBucket.SEOURLName});}
@Html.RenderAction() generates a write call to output something on the page and in your case you are not doing so because RenderAction renders the result directly to the Response. 
Instead of
@Html.RenderAction()
Use
@{Html.RenderAction();}