planets are point like Need Help. I have a problem with my 50 mm objective with 500mm focal length refractor telescope. I can see moon clearly. I have 18 mm and 9 mm eyepieces.

I see Jupiter and Venus as a bright point when focused at 30x or 60x and I see white disk when out of focus. While I have successfully resolved double stars with it and I saw Pleiades star cluster clearly with it, I cant see the moons of Jupiter.

Should I buy 3x Barlow to see the bigger image? is low magnification is my problem? 
Or there is another solution to this problem.?
You should definitely be able to see the 4 main moons of Jupiter. You won’t need additional magnification - they can be seen through 10 x binoculars. It’s possible that when you looked the moons were close to or behind Jupiter, so worth trying again. Or it may be that James is right and you were looking at a star. 
As for the bands on Jupiter, these are quite subtle but at 60x magnification, 2 dark bands should be visible. Don’t expect to see the Great Red Spot, at least initially.