Huffman dictionary provided does not have the codes for all the input signals

I seem to be having a problem passing the string and dictionary through the huffmanenco function. I've tried almost everything, but the I keep getting the error that the Huffman dictionary does not have all the input codes. Yet I'm positive it does.

%%HUFFMAN TEST
clear all; close all; clc;

sig = ['a'; 'b'; 'c'; 'd'; 'e'; 'f'; 'g'; 'h'; 'i'; 'j';...
            'k'; 'l'; 'm'; 'n'; 'o'; 'p'; 'q'; 'r'; 's'; 't';...
            'u'; 'v'; 'w'; 'x'; 'y'; 'z'; ':'; ' '; ','; '.'];

% Get probability
char_count = zeros(30,1);

for i = 1:30
    for c = sig(i)
        char_count(i,1) = length(find(sig == c));
    end
end

sym_prob = char_count / sum(char_count);

% Huffman Dictionary
% symbols = cellstr(symbols); % Still doesn't work in huffmandict, so try manually typing out again with curly braces
sig = {'a'; 'b'; 'c'; 'd'; 'e'; 'f'; 'g'; 'h'; 'i'; 'j';...
            'k'; 'l'; 'm'; 'n'; 'o'; 'p'; 'q'; 'r'; 's'; 't';...
            'u'; 'v'; 'w'; 'x'; 'y'; 'z'; ':'; ' '; ','; '.'};

[dict, aveLength] = huffmandict(sig, sym_prob);

% Process signal
str = 'A technique is developed to construct a representation of planar objects undergoing a general affine transformation. The representation can be used to describe planar or nearly planar objects in a three-dimensional space, observed by a camera under arbitrary orientations.';
str_int = bin2dec(dec2bin(str));

sig = cell(size(str));
for i = 1:length(str)
    sig{i} = char(str_int(i));
end

% Encode & Decode
sig_enco = huffmanenco(sig, dict);
dsig = huffmandeco(sig_enco, dict);