Sprites Show up Not according to Z order, is this bug?

So, here is the situation

I got several sprites and the z order is

Sprite 1

Sprite 2

Sprite 3

Sprite 4

Sprite 5

It only consist of 1 layer, and strangely my sprite number 1 always shown under the sprite number 2 and 3 which are the background

So what is this and why is this happen?

Any suggestion?

NVM, something wrong with the construct 2, once I restarted the program it works perfecly normal again