Concatenate fields of two different structures based on two conditions results in Index exceeds array bound help!

I have two structures with Struct1(1 by 40) fields Date and Time (scalars), and Struct2(1 by 100) fields Date1 and Time1 which are vectors. Now I want to attach the fields Date1 and Time1 in struct2 to struct1 if Date=Date1, and Time=Time1. Notice one is scalar and other is vector. My code is as follows. But i get the error as Index in position 1 exceeds array bounds.

Any suggestion is highly appreciated !!!

StartTime=[];
for  ii = 1: length(Struct1)
     for jj = 1: length(Struct2)
          for kk = 1: length(Struct2(ii).Time1)
            if Struct1(ii).Date==Struct2(jj).Date1(kk,1) || abs(Struct1(ii).Time - Struct2(jj).Time1(kk,1)) <= 3000
                       Struct1(ii).StartTime(kk,1) = vertcat(StartTime,Struct2(jj).Time1(kk,1)) ;
            else jj = jj+1; 
            end
          end  
     end 
end