Minecarts can not turn

minecarts can not go over normal rails that are turning, the minecart will act as if the turned rail is a solid block and just change directions when it hits the rail, i also tried creating a 2x2 square of normal rails to make a circle, when placing minecarts on the rail they would not move from the block they were placed on, even when i physically tried pushing the minecart all it did was "vibrate" in place.