Random Plot coming from nowhere?

Code:

function [ak] = myNF(A,B,T,N)
n=0:1:N-1
ak=myDTFS1(A*cos(25*n*T)+B*cos(5*n*T)); %Part 3A
akmag=abs(ak)
figure
plot(n,akmag)  %part e,1
hold on
title('n,asjdf;lkajds;flkajd;sfkajsd;flkjadfak');
hold off

%figure
%plot(n,akmag)
%hold on
%title('n,ak2');
%hold off

kk=myCONVLin(A*cos(25*n*T)+B*cos(5*n*T),n*T)        %Part 3B
figure
plot(n,kk)
hold on
title('n,kk');
hold off

a=1:1:50;
q=1:1:50;
X(q)=A*cos(25*q*T)+B*cos(5*q*T)                     %Part 3C
X(q+a*N) = X(q); %makes it periodic
%H(n+a*N) = H(n); %makes it periodic
bk=myDTFS1(A*cos(25*n*T)+B*cos(5*n*T));
bkmag=abs(bk)
figure
plot(n,bkmag)
hold on
title('n,bk');
hold off
end

So, the function is supposed to make 3 plots. n,asjdf;lkajds;flkajd;sfkajsd;flkjadfak n,kk and n,bk.

The n,kk and n,bk plots are working perfectly. however the n,asj.... plot is not showing up. Instead, its this weird plot that I dont know what it is.

However, if i try to plot ak2, the function will give me 4 plots. The n,kk plot, the n,bk plot, the n,adjdf... plot and once again the weird plot that i dont understand. The function is NOT giving me the ak2 plot.

Here is the myDTFS1 code:

function [c] = myDTFS1(f) 

syms j k w n;
N=length(f);    %takes in the length of the vector
c = zeros(1,N); %sets the values of the matrix to 0
a=exp(-1i*(2*pi)/N);    %part of the analysis equation to make it easier to compute.

for n=1:N
    for k=1:N
        x=(1/N)*f(n)*(a.^((n-1)*(k-1)));    %n-1 and k-1 is a way to get around matlab not taking in 0's.
        c(k)=c(k)+x;
end
end
end

as you can see, no plots should be made in mydtfs1 function. Any ideas?

[Image Analyst]

Please supply values for A,B,T,N so we can call your function.