Flattering someone to get something is renting their good mood. The lease runs out fast.

Praise handed out to get something works exactly once and then starts reading as a signal that you want a favor. People are quicker at spotting this than they get credit for, especially the ones who get flattered often. What you bought was a few minutes of goodwill, and after that every genuine compliment you ever give them arrives under suspicion. That is a steep price for a small ask.

Say the true version instead, and say it at a moment when you obviously want nothing. Then make the ask separately and plainly. People say yes to directness more than you expect.