Sometimes, it's obvious to all concerned that they're onto an absolute winner. "This film will make Star Wars look like a flop" they cry.
"And seeing as there's definitely going to be a sequel or two, we may as well set it up nicely so that the whole thing flows properly when hordes of fans watch the trilogy in one sitting in ten years' time".
Bless their optimism, but it doesn't always work out like that. Here's ten films that were begging to be continued, but were left hanging in the wind, like a broken street sign which solemnly reads "No Chance Close (Cul de Sac)".