vector aligned_allocator not taking desired value

my question might seem too easy but I am struggling it with many hours. I am trying to write an application where I am sending data to an openCL kernel from a host file and getting the result back. for inputting the data, first the data need to be put in a vector as below:

vector<float, aligned_allocator<float>> source_a(DATA_SIZE,10);

https://github.com/Xilinx/SDAccel_Examples/blob/master/getting_started/host/errors_cpp/src/host.cpp

Suppose DATA_SIZE is 20, it put 10 at all the locations. I tried changing the syntax like below, but it do not put the desired values.

vector<float, aligned_allocator<float>> source_a(DATA_SIZE);
 for(int j=0;j< DATA_SIZE;j++){
   source_a.push_back(phi_val[j]);
 }

Please help me with the syntax of vector.