Error in Plot Function

I am reciving the following error when trying to plot:

Error using plot

Vectors must be the same length.

Error in lab2 (line 50)

plot(X2,twoHZ,'b--');

code:

figure (1)
subplot(2,3,1)
plot(X2,twoHZ,'b--');
xlabel('time(sec)')
ylabel('height (m)')
title('Two Hz')

Any help would be much apprciated!

[Walter Roberson]

We do not know what the sizes of X2 and twoHZ are, or how they are constructed.

All we know from the error message is that X2 and twoHZ are different sizes.