Error on nested loop?

I have programmed as one big for loop contain two small loop. But the problem is first loop(%TOP CHECKING) only running. sencond loop(%Down checking) not running.

my code bellow

or=1; [r c d]=size(RGB);

for i=1:tblob x=shape(i).cen(1,:); y=shape(i).cen(2,:); xi=x; yi=y; w=0;flag=0; %TOP CHECKING

for(trail=1:1000) color_val=color(y,x); RGB(y,x,1)=240; RGB(y,x,2)=31; RGB(y,x,3)=191;

if((color_val==shape(i).color)&w==0) if(r>y) y=y+1; end %x=x-1; else if (color_val==White) w=1; if(r>y) y=y+1; end %x=x-1; else if(color_val==Black) flag=1; else %T juction if (color_val==[240,31,191])

                               order(or).order=[xi,yi,x,y];
                               or=or+1; 
                               RGB=line(xi,yi,x,y,RGB);   
                               flag=1;

                            else
                for i=1:tblob
                  xa=shape(i).cen(1,:);
                  ya=shape(i).cen(2,:);
                   
                                    if (color_val==shape(i).color)
                                        if(x-40<xa<x+40)
                                            if(y-86<ya<y)
                                                xj=xi; 
                                                yj=ya;
                                                shape(i).cen(1,:)=xi;
                                                order(or).order=[xi,yi,xj,yj];

                                                or=or+1; 
                                                RGB=line(xi,yi,xj,yj,RGB);   
                                                flag=1;

                                            end
                                        end
                                    end
                                end
                            end
            end
          end
                end
               if (flag==1)
                 break;
               end
            end
             
            %DOWN CHECKING

for(trail=1:1000) color_val=color(y,x); RGB(y,x,1)=240; RGB(y,x,2)=31; RGB(y,x,3)=191;

if((color_val==shape(i).color)&w==0) if(r>y) y=y-1; end %x=x-1; else if (color_val==White) w=1; if(r>y) y=y-1; end %x=x-1; else if(color_val==Black) break; else %T juction if (color_val==[240,31,191])

                               order(or).order=[xi,yi,x,y];
                               or=or+1; 
                               RGB=line(xi,yi,x,y,RGB);   
                               flag=1;

                            else
                for i=1:tblob
                  xa=shape(i).cen(1,:);
                  ya=shape(i).cen(2,:);
                   
                                    if (color_val==shape(i).color)
                                        if(x-40<xa<x+40)
                                            if(y-86<ya<y)
                                                xj=xi; 
                                                yj=ya;
                                                shape(i).cen(1,:)=xi;
                                                order(or).order=[xi,yi,xj,yj];

                                                or=or+1; 
                                                RGB=line(xi,yi,xj,yj,RGB);   
                                                flag=1;

                                            end
                                        end
                                    end
                                end
                            end
            end
          end
                end
               if (flag==1)
                 break;
               end
            end

end

imshow(RGB)