Index exceeds matrix dimensions - Error

Hello, I am trying to plot the two functions on the same graph and am unable to label both y-axis. Could someone please tell me what I am doing wrong?

t = 0:20;

y1 = (100*sin(pi/4).*t)-(.5*9.8*t.^2);

y2 = 100*sin(pi/4)-9.8.*t;

a = plotyy(t,y1,t,y2);

title('Problem 5.26')

xlabel('time, sec')

ylabel('Position')

ylabel(a(2),'V(t) Vertical Direction')

[Adam]

Your code works fine for me (in R2014b)

[Chad Greene]

Works fine for me too in R2012b. Try typing close all; clear all at the beginning. You may have some leftover data from previous code lingering around.

[Alyssa]

I have R2013b. It's only the ylabel that keeps giving me trouble. The xlabel and title show up but once I put that ylabel in it gives me the error.

[Alyssa]

Nevermind. I ran it again and it worked. Today just isn't my day.

[Guillaume]

And what error is that?