LNK2001 error occurs when building but not by Debugging

I have written a programm using Allegro 5 and wanted to build it in Visual Studio 19 but the build log states that there are some LNK2001 errors when I try to initialize the allegro addons I am using.

The Log:

Backend.obj : error LNK2001: unresolved external symbol __imp__al_init_image_addon
Backend.obj : error LNK2001: unresolved external symbol __imp__al_init_ttf_addon
Backend.obj : error LNK2001: unresolved external symbol __imp__al_init_font_addon
Backend.obj : error LNK2001: unresolved external symbol __imp__al_draw_filled_triangle
Backend.obj : error LNK2001: unresolved external symbol __imp__al_init_primitives_addon
E:\Projects\AllegroProgramm\Release\Allegro.exe : fatal error LNK1120: 5 unresolved externals

These are my includes:

#include "allegro5/allegro.h"
#include "allegro5/allegro_image.h"
#include "allegro5/keyboard.h"
#include "allegro5/keycodes.h"
#include "allegro5/allegro_native_dialog.h"
#include "allegro5/allegro_ttf.h"
#include "allegro5/allegro_font.h"
#include "allegro5/allegro_primitives.h"

And thats how I call the al_init_... functions:

al_init();
al_install_mouse();
al_install_keyboard();
al_init_image_addon();
al_init_font_addon();
al_init_ttf_addon();
al_init_primitives_addon();

And as I said in debug mode it works but not in release I have no clue why!

Thanks

In Visual Studio most of the project configuration is separate for Debug and Release mode.

You probably added the Allegro library (.lib file) in Debug mode but forgot to also add it in Release mode.