Cannot understand Credit limit Overdue check

[LeThuHang]

Hi expert

I create Sale Order but get error: Oldest open item is 219 days overdue

I check BP and see Oldest Item amount =0, Days= 219.

FBL5N have no open invoice, customer has large advance amount.

This error after we performed an upgrade from ECC to S/4HANA. 

Are there anythings I miss understand. pls help. thank you very much.