Why won't this function to generate a beta binomial distribution work?

I am new to function writing and don't understand the error message I am getting when I try to run this function

function y=bbinopdf(x,n,a,b)
y= beta(x+a,n-x+b)/beta(a,b)
end

Define values as

x=[1:1:100];
a=1;
b=1;
n=10;

I can enter bbinopdf(x,n,a,b) with no error but then there is no output. If I use y=bbinopdf(x,n,a,b) I get

Error in bbinopdf (line 1)
function y=bbinopdf(x,n,a,b)

Output argument "y" (and maybe others) not assigned during
call to
"/Users/awetten/Documents/MATLAB/bbinopdf.m>bbinopdf".

Can anyone help- please?