Example Code cannot Work?

[snowbird123]

sir,i can run the deomo .i need some help.
I run the exmaple from arduino IDE ,just as picture snaped below. complie and upload it by stlink with no errors.But there is no signal in these pins ： uint8_t custom_rgbpins[] = { PA15, PA0,PA1,PA2,PA3,PA4,PA5 }; // CLK, R0, G0, B0, R1, G1, B1.
The pin PA15 is always high. now i dont konw how can i do next.