Check the angle three times before you shoot. Good luck, fearless witch!

In Classic mode levels like this, the "ceiling" often sits very high. Dropping a large cluster of bubbles requires clearing specific "anchor" bubbles. Failing to hit these anchors results in wasting turns chipping away at the outer layers, which usually depletes the bubble count before the objective is met.

If you have attempted more than 20 times without success, you may be in a "soft lock" caused by the game's random seed.