First Spaceship on Venus

Were it not for the really terrible English-language dubbing, this would actually have made for quite a decently made sci-fi feature. When evidence is found from a meteor that there might be intelligent life on Venus, an international team is assembled to travel in the "Cosmocrator" to that distant world to investigate. En route, they manage to decipher some of the writing found on the meteoric chunk and conclude that the folks from Venus had actually contemplated invasion of the Earth at the start of the 20th Century - might they be flying into the lions den? The space ship effects are all pretty much "Forbidden Planet" (1956) and the actors, though admittedly pretty poor, reflect a diversity of races and nations as they hurtle through space. Once on the planet, however, this starts to come apart at the seams a bit - they must evade an encroaching mass of mud/treacle/chocolate and their destination, that definitely shows signs of having had a developed civilisation at one point, seems to want to eliminate them all... Can they make it back home? It's no worse than any of the "Outer Limits" style movies we'll have sat through over the years, and had it been subtitled I might have actually quite enjoyed it. It even has an underlying theme that might just be worth bearing in mind 60 years later, too.