Does anyone have any tips on ENSURING that when you put a player up for auction, they actually sell?

I have a DR, 19 yrs old 4 star, fast trainer.I expected him to sell within the first day of being listed. 1 week later he's still here! What am I doing wrong?

My team as of now is DEPENDING on the sale of this player. Don't ask me how. It.Just.is.

Help!