code showing "Too many output arguments", how to resolve it?

I am trying to detect lines using following code using hough transform but having this error- "Too many output arguments". I am giving input a 420*560 grayscale image. code is following:-

    function HTPLine(inputimage)
    %image size
    [rows,columns]=size(inputimage);
    %accumulator
    rmax=round(sqrt(rows^2+columns^2));
    acc=zeros(rmax,180);
    %image
     for x=1:columns
    for y=1:rows
    if(inputimage(y,x)==0)
    for m=1:180
    r=round(x*cos((m*pi)/180)+y*sin(m*pi)/180);
    if(r<rmax && r>0) 
     acc(r,m)=acc(r,m)+1;
    end
    end
    end

[Image Analyst]

Which line is throwing the error? Please copy and paste the entire error message - all the red text - so we don't have to guess. You do know that hough() and houghlines() are in the Image Processing Toolbox, don't you? So you don't have to do this yourself.