Plot of confidence interval with fill

Hi, I have a confidence interval (CI) I would like to plot together with its average. I have used the command fill to create the grey CI area and don't get the results that I want. My data is

mu_diff
0.004228176
-0.000889339
-0.016775836
-0.023576712
-0.041489385
-0.050768254
-0.621729693
-0.634756996
-0.640305162
-0.648905396

CI	
0.004041487	0.004414864
-0.001080781	-0.000697896
-0.016971981	-0.016579692
-0.023777484	-0.02337594
-0.041694683	-0.041284086
-0.050977948	-0.050558559
-0.621943623	-0.621515762
-0.634974968	-0.634539023
-0.640526947	-0.640083377
-0.649130726	-0.648680066

and the lines I have written are

x_axis = 61:70;
x_plot =[x_axis, fliplr(x_axis)];
y_plot=[CI(:,1)', flipud(CI(:,2))'];
hold on
plot(x_axis, mu_diff, 'black', 'linewidth', 1)
fill(x_plot, y_plot, 1,'facecolor', 'red', 'edgecolor', 'none', 'facealpha', 0.4);
hold off

and this is the result

Clearly this is not correct. What is going wrong here?