ncelab: *F,INTERR: INTERNAL ERROR , debug

Hi,

Could anyone help to debug this issue is it a tool issue or code issue.....

I'm getting the following error for simulation....the code compiles fine..i have written a separate interface file along with clocking block in it....code for interface file is not shown here.....

`timescale 1ns/1ns
module top;
bit Clk24 = 0;
bit ResetN = 0;

always #12 Clk24 = ~Clk24;

gfsktx_top_if tx_gfsk_if(Clk24);

GfskTxTop dut ( .Clk(Clk24),
                .ResetN(tx_gfsk_if.ResetN),
                .S2PIn(tx_gfsk_if.S2PIn),
                .ValidIn(tx_gfsk_if.ValidIn),
  .TxEnable(tx_gfsk_if.TxEnable),
                .Gfsk2DacI(tx_gfsk_if.Gfsk2DacI),
  .Gfsk2DacQ(tx_gfsk_if.Gfsk2DacQ),
                .ValidOut(tx_gfsk_if.ValidOut)
                  );

//classes
class gfsktx_bfm;

 //virtual gfsktx_top_if sigs;
       
 //function new
 //function new(virtual gfsktx_top_if sigs);
 // tx_gfsk_if = sigs;
 //endfunction: new

 //task reset sequence
 task resetsequence();
 
  //semaphore sem = new(1);
  //if(!sem.try_get(1)) $stop;

  $write("task reset sequence entered\n");
  tx_gfsk_if.ResetN  
  tx_gfsk_if.S2PIn  
  tx_gfsk_if.TxEnable 
  tx_gfsk_if.ValidIn 
  repeat (2) @top.Clk24;
  
 
  //sem.put(1);

 endtask: resetsequence
 
 //checking reset
 task resetcheck();

  //semaphore sem_1 = new(1);
  //if(!sem_1.try_get(1)) $stop;
 
  @Clk24;
  assert(tx_gfsk_if.Gfsk2DacQ == 'b0);
  assert(tx_gfsk_if.Gfsk2DacI == 'b0);
  assert(tx_gfsk_if.ValidOut == 1'b0);
  @Clk24;

  //sem_1.put(1);

 endtask: resetcheck

 task load_data(integer count);
  int cnt;

  cnt = count;
 
  //semaphore sem_2 = new(1);
  //if(!sem_2.try_get(1)) $stop;

  tx_gfsk_if.ResetN  
  tx_gfsk_if.S2PIn 
  tx_gfsk_if.TxEnable 

  while(cnt != 0)
  begin
   tx_gfsk_if.ValidIn 
   @Clk24;
   tx_gfsk_if.ValidIn 
   repeat(23)@Clk24;
   cnt--;
  end

 endtask: load_data

endclass: gfsktx_bfm

gfsktx_bfm gfsktx;
//gfsktx_test gfsktx_test();
initial
 begin
  gfsktx.resetsequence();
  repeat(20) @Clk24;
  gfsktx.resetcheck();
  repeat(20) @Clk24;
  gfsktx.load_data(20);
  repeat(300) @Clk24;
  $finish;
 end  
endmodule: top