AT89C51RD2, flash monitor says Target Dll has been Cancelled, Debugger aborted

Hi,I'm trying to debug my program using keil flash monitor on an AT89C51RD2 running at 24MHZ, I've downloaded @57600 keil's genuine AT89C51RD2 flashmon driver, with no problem, I've set BSB(Boot Status Byte) to non zero( 0xFC or 0xFF) and SBV(software boot vector) to 0xE0 and Enabled Boot loader Jump Bit( BLJB) as asked for in the document, every time I start the debuger( I've chosed use Keil Monitor 51 driver in my project target options ) I get the message "Target Dll has been Cancelled, Debugger aborted"
I couldn't find any information in keil documents on why this happens, can anyone give me a hint why this happens, please!
I really appreciate any hint.
Oh... one thing else when the chip is off keill shows a dialog box Connection to target system lost

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