It would help to have your code and data.
The legend entries correspond to the lines being plotted, and if there are more than one line, this can cause ptoblems.
You may need to speciifically reference each separate plot call.
Example —
x = linspace(0, 1, 1E+3).';
y = sin(2*pi*x*(1:5:25)) + (1:5)
figure
plot(x, y(:,1:3), 'b')
hold on
plot(x, y(:,4:5), 'r')
hold off
grid
legend('y_1','y_2') % No Specific References
figure
hp1 = plot(x, y(:,1:3), 'b');
hold on
hp2 = plot(x, y(:,4:5), 'r');
hold off
grid
legend([hp1(1) hp2(1)], 'y_1','y_2') % With Specific References
.
