If statement not working?

this is my code - it is supposed to be a binary array, where the length of time (through the array) that the "1"s are held is determined by "time" - why is the if statement not working based off of the output of "time"? all i get is a 60X96X10 array of zeros.

function cubefinal = sensingmatrix3d(~)
exposure=zeros(60,96,10);
time=randi([3 7]);
if time==3
   for j=1:size(exposure,1);
    for jj=1:size(exposure,2);
        randnum=randi([1 8]);
        exposure(j,jj,randnum:randnum+2)=1;
    end
   end
elseif time == 4 
    for j=1:size(exposure,1);
    for jj=1:size(exposure,2);
        randnum=randi([1 7]);
        exposure(j,jj,randnum:randnum+3)=1;
    end
    end
elseif time == 5 
    for j=1: size(exposure,1);
    for jj=1:size(exposure,2);
        randnum=randi([1 6]);
        exposure(j,jj,randnum:randnum+4)=1;
    end
    end
elseif time == 6 
    for j=1:size(exposure,1);
    for jj=1:size(exposure,2);
        randnum=randi([1 5]);
        exposure(j,jj,randnum:randnum+5)=1;
    end
    end
elseif time == 7 
    for j=1:size(exposure,1);
    for jj=1:size(exposure,2);
        randnum=randi([1 4]);
        exposure(j,jj,randnum:randnum+6)=1;
    end
    end
   cubefinal=exposure;
end

[Geoff Hayes]

Rather than posting a duplicate question, please just further the conversation at http://www.mathworks.com/matlabcentral/answers/232187-why-is-the-if-statement-not-working. Two answers have already been provided so it is there that you should either provide more details or ask for more help.