after few times programming debugger can't recognize microcontroller(stm32f101vbt6)

hello every one
I'm using stm32f101vbt6 by st-linkv2 programmer.
after few times programming my micro i get this message : no target  connected. so my debugger can't recognize microcontroller.


i checked every connection and it was ok I tried j-link programmer but j-link couldn't recognize micro too. so i changed micro and programmed micro few times and this problem happend again for three times.
in my pcb design i connect SWDIO from programmer to micro and between them i put 330 ohm resistor.same thing for SWCLK as the picture uploaded.


in my board when programming i'm connect my power plug on from adapter
i don't know why this happening.is it because of ESD(Electrostatic Discharge)?Is my design has any problems?
i didn't have this problem for stm32f103.

appreciate your help.

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