plotting a function from anothe .m file , please help

i am facing a problem plotting this function

objfun244.m

function f=objfun244(tp)
% The objective function: total cost per unit time if replacement interval is tp
% Assumption: The smallest time unit is week. 

% f: total cost per unit time
% tp: Length of the time interval in Weeks (preventive replacement interval)

global Cp Cf   % cost of preventive replacement and failure replacement, respectively
T =ceil(tp);

% f: total cost per unit time C_tp
f=(Cp+Cf*HT(T))/tp;

% % Test
% objfun244(4)

then on another .m file which is called plotting2.m here is the code i wrote

clear all;

clc;

t = i:1:12;

plot(t,objfun244(t));

grid on

xlabel('t')

ylabel('COST')

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there is another function called H T , here is its code

function H=HT(T)
% The recursive function H(T)
% Calculate the Expected number of failures in (0,T], for Weibull
% Distribution
% Assumption: T's unit is week, the smallest time unit. 

% H: the Expected number of failures in (0,T] 
% T: length of the time interval in weeks (preventive replacement interval)
% T is a nonnegative integer: 0, 1, 2, 3, ...

global Al Be % Alpha and Beta for the Weibull distribution, respectively  % #####
global HT_vec HT_flag % Calculated H(T) values: HT_flag(T)=1 if it has been calculated

H=0;   % H(0)=0: initial value

if T<0.001

%     H=0;   % If T=0, H(T)=0;

elseif HT_flag(T)>0
    % If HT(T) has been calculated, used the saved value    
    H=HT_vec(T);  % Assign the value from HT_vec

else
    % Otehrwise, recursively calculate H(T)
    % i: time from 0 to T-1

      for i=0:(T-1)
          H=H+(1+HT(T-i-1))*(wblcdf(i+1,Al,Be)-wblcdf(i,Al,Be)); % #####
      end
      % Save the calculated H(T) value
      HT_vec(T)=H;
      HT_flag(T)=1;
  end

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i got error : ??? Subscript indices must either be real positive integers or logicals.

Error in ==> HT at 20
elseif HT_flag(T)>0

Error in ==> objfun244 at 12
f=(Cp+Cf*HT(T))/tp;

Error in ==> plotting2 at 11
plot(t,objfun244(t));

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pleaseeee hellpppppp