ISD51 software

I just studies software debug using ISD51 through AT89C51SND1C's UART port.but now i have some questions. let me describe it.
I write a simple main program in keil uvsion2 ICE(below), then add some program and set uvision according to the help file:isd51.htm. I have a good luck, after do that, the uvison can connect to my user board , the program can run step by step using F11. but some quesitons puzzle me:
when debugging,
1) i set a software breakpoint , but it can not work.
2) i can not stop running when the program is running.
3) i can not step over a function(exmple :Delay_10ms();) use shortkey: F10.

below is my main.c

#include "lib_mcu\compiler.h" /* compiler definitions */
#include "lib_mcu\regsnd1.h" /* component declaration */
#include "lib_mcu\extsnd1.h" /* component extended declaration */
#include "ISD51.H"

sfr p4 = 0xc0;

extern void in_system_prog (void);
static void main(void);



static void Delay_10ms(void)
{
unsigned char i;
unsigned int j;
for(j = 0; j < 40; j++){
j++;
for (i = 0; i < 200; i++);
}

}
static void seiral__initial(void)
{
(CKCON |= MSK_X2); //set x2 mode
SCON = 0x50;
PCON |= (1 << 7);
BRL = 230; /* set 38400 baud @ 16MHz */
BDRCON = 0x1E;

EA = 1;
//ES = 1;

}

void main(void)
{
seiral__initial();


#if 0 // init ISD51 and start user program until the uVision2 Debugger connects
ISDinit (); // initialize uVision2 Debugger and continue program run
#endif

#if 1 // init ISD51 and wait until the uVision2 Debugger connects
ISDwait (); // wait for connection to uVision2 Debugger
#endif


p4 = 0xff;

while(1){
#if 1 // init ISD51 only when the uVision2 Debugger tries to connect
ISDcheck(); // initialize uVision2 Debugger and continue program run
#endif
// ES = 1;
Delay_10ms();

p4 = ~p4;
#if 0 // you may use ISDbreak when ISD51 is started with ISDcheck or ISDwait

ISDbreak (); // hard coded stop (breakpoint)


#endif
}
}

Somebody can help me ?

Regards,
hexiuchi (&#20309;&#20462;&#27744;&#65289;.
Namtai Electr. Co. PRC
E-Mail: xche@namtai.com.cn
Tel:(86755)27495818-3433
Fax:(86755)27497143