Parents are hard to please often, mainly because they expect so much of you, often extremely unrealistic. However, this does not mean that they aren't proud of you. Sometimes, parents hide their emotions but will show it in little ways like giving you a present, money, doing something nice for you etc. Some people find it helps to tell their parents how they feel about the way that they act towards them so that their parents have a better understanding of the way that they react towards their parents and it sometimes helps them to realise what their actions are doing. I hope this information helps.
Parents generally view their children as an extension of themselves, and therefore put the sometimes perfectionist beliefs they have of themselves on others. It's not anything you are doing, but rather what they are thinking and feeling.
I don't know if this fits into your problem but from my experience some parents have an idea of their children from the child's birth. They make expectations that their children can't or don't feel like they should follow. Maybe your parents have similar expectations and they're trying to fit you into a mold that you don't fit in.
It's literally impossible to please everyone all the time, your parents included. They are of a different generation and so have different values, perspectives, expectations and dreams. All parents do the best job they can
Parental expectations often conflict with our own desires. This may be because our interests and strengths do not match what our parents' expectations, or possibly what their "vision" of who they wanted you to be aligns with our own. The best course of action is to keep an open dialogue
I believe this happens in most cases because 1) Our parents, like us, are also imperfect individuals and 2) because they're constantly thinking about what's right for their children. While they do love us unconditionally, they also tend to expect us to thrive in the kind of environment they've imagined or hoped we would thrive in. They like to see us doing things or achieving things they hoped we would. And at often times, this is what leads us to thinking we are unable to please them no matter what we do.
To sum it up, we can't please our parents not because we're not enough, but because sometimes, they expect a little too much from us.
But then again, what I just stated is not relevant in every situation.