麻烦帮忙看下为何以下相同语句编写的指标bl1、bl2在图像上显示的不一样
nn1:=barslast(cross(sellvol,buyvol))+1;
mmm:=sum(buyvol,nn1);
nnn:=sum(sellvol,nn1);
nn2:=barslast(cross(buyvol,sellvol))+1;
mmmm:=sum(buyvol,nn2);
nnnn:=sum(sellvol,nn2);
if barslast(cross(buyvol,sellvol))<barslast(cross(sellvol,buyvol)) then ml1:=mmmm;ml2:=nnnn;
if barslast(cross(buyvol,sellvol))>barslast(cross(sellvol,buyvol)) then ml1:=mmm;ml2:=nnn;
bl1:ml1,colorwhite;
bl21:ml2,COLORMAGENTA;

搞不懂为何图中粉红色的bl2指标本该为0的地方不为0,而白色的bl1却正常?