Cannot find Multiple Roots using Bisection

Function 1:

function    f = example1( x, oldroots)
Bi = 0.5;
             f = 1-x*cot(x)-Bi;;

          if  length( oldroots ) > 0 ,
               f = f / polyval( poly ( oldroots ), x );
          end

Function 2:

function  x  =  findallzeros( fhandle, xguess, maxroots)
  x   = [ ]                ;

    if nargin==1
        xguess =0;
        maxroots = 1;
    end

    if nargin==2
        maxroots  = 1;
    end

    nroots = 0;

    while nroots<maxroots
        if  abs(feval(fhandle,xguess,[ ]))<=1e-16,
            xroot=xguess;
        else
            [xroot,val,flag] = fzero(fhandle,xguess,[ ],x);
            if flag <= 0
                return
            end
        end
        x=[x,xroot];
        nroots=nroots+1;
        xguess=xguess+0.01;
    end

Problem:

Cannot seem to adapt this code to finding all the roots in a given region (0 < x =< 15) for my defined function, f.

It will only display one root in that interval, or two if I manually change the initial "guess". Any thoughts?