React Native Android Slider cannot slide vertically on device

I've used the Slider component on React Native 0.43 using the following code. It works fine for iOS as it has a nice big "button" for user to hold and drag. But on android it is just a small dot and I find that I could not drag it vertically (1/10 tries are successful). I find that the "drag" get captured by the ScrollView in the background instead. Help?

      <Slider
        minimumValue={minValue}
        maximumValue={maxValue}
        step={step}
        style={styles.slider}
        value={parseInt(input.value)}
        onSlidingComplete={onSlidingComplete}
        onValueChange={onValueChange}
      />

  slider: {
    marginRight:-100,
    marginLeft:-100,
    width:250,
    transform: [
      { rotateZ : '-90deg' },
    ],
  },