question about PSL

Hi, all:

I want to do assertion check in a "for" loop, and I want to do assertion check in every loop(totally 10 times in my file), but it seems that the assertion check only done once, and at the very beginning of the file instead of after going into the loop.       ncsim shows "ncsim: *E, ASRTST (./top.v, 55): (time 0 FS) Assertion top.assert_P1 has failed (1 cycles, starting 0 FS)".

following is my code, Can you help me?

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class rand_cov;
   rand bit[4:0] data_a;
endclass

module top;
   int i;
   int succ;
   bit[4:0] data;
  
   rand_cov cov_t;
  
   initial begin
      cov_t = new();
      for(i=0; i<10; i++) begin
           $display("NO. %d", i);
           succ = cov_t.randomize();
           data = cov_t.data_a;
           $display("data = %0d", data);
           //psl property P1 = always ( !(data == 14) );
           //psl assert_P1: assert P1;
      end  
   end
endmodule