How to get the patch function to fill in between 2 lines ?

I am trying ti shade the space between an upper and lower limit. Time is a categorical variable so I created 'x' as a numerical array of the same length. But when i plot, it splits the graph into polygons but doesn't fill them. Can someone help with where I'm going wrong?

plot(time,y1);
hold on 
plot(time,y2);
x = (1:1:12)';
patch([x fliplr(x)].',[y1 fliplr(y2)].','b');

[Ameer Hamza]

Without the variables used in this code, it is difficult to see the issue.

Answer 1

[Walter Roberson]

%create some data to illustrate the code
time = categorical({'t01', 't02', 't03', 't04', 't05', 't06', 't07', 't08', 't09', 't10'});
x = 1:length(time);
y1 = x.^2;
y2 = x.^3 / 3 - 2*x.^2 + 5; 

%now do the plotting
plot(time, y1, time, y2);
hold on
fill([time fliplr(time)].',[y1 fliplr(y2)].', 'b', 'edgecolor', 'none', 'facealpha', 0.1);

fill() uses patch with face colors set appropriately.