My STLINK V2 debugger is giving "error: Target not connected" while flashing in STM32F401VBT6 controller? Please tell me the default connections of STM32F401VBT6 while flashing and debugging?

I have given 3.3V to all VDD,VDDA,VBAT,VREF+ with capacitive filtering (100 nf & 1uf) as per datasheet. BOOT0 pin is connected to GND. SWDIO and SWCLK connected to debugger pins. Still it is giving same error.

when BOOT0=1, flashing is done but it gives debugging problem.In debugging mode, debugger does not display data of registers.

Please give me the solution for this error.