You don't unlock the next yellow brick yourself, it changes daily at midnight (French timezone).
So on the first day you are on the first step and can unlock the first flower, then the second day the second step and the second flower, etc.
I assume you don't live in France? No problem, you can see the time above the "recent messages" on the game:
Every day you can only solve 3 puzzles, and sometimes I get the same bug as you, when I complete a puzzle, go to the next one, can't move the pieces, refresh the page and it is the first puzzle again. What I do to be sure is that I save the puzzle when it arrives, then refresh the page, to be sure.
Hope that helps! ^^/