Can't download Keil MDK generated code on to STM32F411E-Disco Board

[MRamy.1]

I created a new project on STM32CubeMX and I started the project with MCU Selector. I selected the STM32F411VETx mcu and I started the project. All pins were reset. GPIOD Pin 15 I made an output. The RCC I chose High Speed Clock (HSE): Crystal/Ceramic Resonator. In the SYS I chose Debug: Serial Wire. Next I generated the code for MDK Keil 5 with the default settings. When I open the project in Keil MDK 5 and build it everything is perfect. When I try to download the code onto the board I get the Error: "No-STlink was found". I have ST-LINK on my board and it works fine since I have used it before. How can I fix this problem. Thanks

[Tesla DeLorean]

It could be open/held by another instance of the program, or another tool, ie ST-Link Utilities or STM32 Cube Programmer.

It might be due to other errors, if for example it can't talk to the target due to pin configuration, or low power modes. Try jumpering BOOT0 HIGH

[MRamy.1]

I choose the STM32F411E-Disco board with the STM32F411VETx MCU on the board and I left all of the default setting as they are I didn't change anything. I choose to generate the code for Keil MDK 5. I opened the code in Keil MDK 5 and I build the code everything is fine there. I tried to load the program on the board and still gives me the error message "No ST-Link". How can I solve this problem? Is the problem with the board?

[Tesla DeLorean]

Check the driver is loaded.

Check if the ST-LINK Utilities can find it.

Check cables and ports.

Avoid hubs and docking stations.

Restart the system.

Try a different system.​