Brush and paint application

Trying to paint a sea scene and having problems.
Q 1 Layer one) sky pale blue and sea almost Ultra marine blue, Layer two.) clouds.
Layer three ) supposed to be the layer to paint in the waves no color appears on the main canvas.
Color white brush Experimental small blot
this will apply color to the blue page on the color mixing pad but not on the main canvas why?

Q 2 I also have had brushes that apply broken color line across canvas to right but full line color to left
straight lines as pulled across taper both ends instead of line from edge to edge or up and down. Why?

Many thanks a .learner.

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