Error setting property 'MarkerFaceAlpha' of class 'Scatter': Value is NaN, or out of range 0.0 <= value <= 1.0

per_all = per_2006_2017/100;% to bring the values in the range of 0 to 1
 
for i = 1:size(xgrid2,1)
    for j = 1:size(xgrid2,2)
        s11 = scatter(xgrid2(i,j),ygrid2(i,j),20,skw_mn_wr(i,j),'filled');
        %size of xgrid2, ygrid2, skw_mn_wr is 119*177
        s11.MarkerFaceAlpha = per_all(i,j); %size of per_all is 119*177
    end
end

I don't have any NaN's in per_all, and all values are between 0 to 1.