Add dk_buttons_and_leds to my project

[ActiTAG]

Hello,

I'm a beginner and I'm a bit lost. It's rather complex to understand everything there is to know. So I ask a lot of questions, sorry.

I was advised to use the lib dk_buttons_and_leds in my project except that despite my #include <dk_buttons_and_leds.h> and the addition in the prj.conf file of these lines:

# Library for buttons and LEDs
CONFIG_DK_LIBRARY=y
CONFIG_DK_LIBRARY_INVERT_LEDS=n

But I get an error: undefined reference to `dk_leds_init'.
Could someone please tell me what I'm missing as information, please?

Thanks.

[ActiTAG]

Edit: I didn't know how to create a project from scratch, so I use the sample threads in the zephyr sample and modify it to do what I want.