Clock init stuck at sys_notify_fetch_result

Question

Hi everyone, 
 
 I trying the DTM example and run with debug, I found the software stuck at dtm clock initial. what is the problem , and how can I fixed it , thanks.

int main ( void ) 
 { 
 int err ; 
 union dtm_tr_packet cmd ; 
 
 printk ( "Starting Direct Test Mode example 
 " ); 
 
 k_sleep ( K_SECONDS ( 3 )); 
 
 // err = bt_enable(NULL); 
 err = bt_disable (); 
 printk ( "bt_disable , %d
 " , err ); 
 
 // irq_disable(RADIO_IRQn );

// printk("mpsl_is_initialized = %d
",mpsl_is_initialized()); 
 printk ( "mpsl_lib_uninit , %d
 " , mpsl_lib_uninit ()); 
 
 // printk("mpsl_lib_init , %d
", mpsl_lib_init());

// mpsl_lib_init(); 
 err = dtm_tr_init (); 
 
 if ( err ) { 
 printk ( "Error initializing DTM transport: %d
 " , err ); 
 return err ; 
 } 
 }