I had ther same problem and was stuck for ages. However, all is not lost! I was using the keyboard to control manny at the time this happened, so i configured the joystick and used that for the controller and he went up the ladder first time!
Once you're up you can go back to using the keys again if u want, but just try and use the joystick to get him up that bit. There's a another ladder in year 4 i had problems with, so just use the same method for that too.