Systemverilog assertion what is the difference between "A throughout B" and "B throughout A"?

In reply to ben@SystemVerilog.us:

sorry for late Ben.

module Testbench;                               
            
  // DUT signals                                
  logic clk;
            
  logic GntA=0;                                 
  logic Busy=0;                                 
  logic DRdy=0;                                 
  logic Done=0;                                 
            
            
  initial begin                                 
  clk = 0;  
  end       
  // Instantiate assertion checkers             
  initial begin                                 
    // Initialize signals                       
     repeat(3)                                  
     @(posedge clk);                            
    /////////////////////////////////////////////////////////////////                           
    GntA = 1;                                   
     repeat(1)                                  
     @(posedge clk);                            
    GntA = 0;                                   
    Busy = 1;                                   
    DRdy = 1;                                   
     repeat(1)                                  
     @(posedge clk);                            
    Done =1;
     repeat(1)                                  
     @(posedge clk);                            
    Done =0;
    Busy =0;
    DRdy = 0;                                   
            
     repeat(14)                                 
     @(posedge clk);                            
            
    // Finish simulation                        
    #100;   
    $finish;
  end       
always #1 clk = ~clk;                           
            
initial begin                                   
        $shm_open("wave.shm");                  
        $shm_probe("AS");                       
end

   
property BPE1;
  @(posedge clk)
    (GntA) |=> Busy[*1:2] throughout DRdy ##0 Done;
endproperty
CHK_BPE1 : assert property (BPE1);



property BPE2;
  @(posedge clk)
    (GntA) |=> DRdy throughout Busy[*1:2] ##0 Done;
endproperty
CHK_BPE2 : assert property (BPE2);
   
endmodule



From BPE1, I get the error " Expected a verilog expression as operand to throughout operator."