OpenGL 3 Shader bug

  c++, glsl, lighting, opengl, shader

we are tasked to create diffuse lighting for a sphere, but we think we have a bug in our shaders. when we put our shader like this:

vertex shader:

#version 330 core

layout (location = 0) in vec3 position;
layout (location = 1) in vec3 aNormal;

uniform mat4 u_MVP;
uniform mat4 model;
out vec3 FragPos;
out vec3 Normal;

void main() {
    //lighting calculations
    gl_Position = u_MVP * vec4(position,1.0);
    FragPos = vec4(model * vec4(position,1.0)).xyz;
    Normal = aNormal;

fragment shader

#version 330 core

layout (location = 0) out vec4 color;

uniform vec3 u_Light;
uniform vec4 u_Color;
in vec3 Normal;
in vec3 FragPos;

void main() {
    // Light emission properties
    // You probably want to put them as uniforms
    vec3 LightColor = vec3(1.0, 1.0, 1.0);
    vec3 ambient = vec3(0.2, 0.2, 0.16);

    vec3 norm = normalize(Normal);
    vec3 lightDir = normalize(u_Light - FragPos);
    float diff = clamp(dot(norm, lightDir), 0.0, 1.0);
    vec3 diffuse = diff * LightColor;

    color = (vec4(ambient,1.0f)+vec4(diffuse,1.0)) *u_Color;
    color.a = u_Color[3];
    //color = vec4(0.0, 0.0, 0.5, 0.1);

When we put the positions with the model we have no diffuse lighting. When we put the FragPos with the coords of the position (FragPos = position;) it kind of works, but the light does not change direction. We should note that the normals of the sphere were calculated by a tutorial and were not a creation of ours. Do we have a glaring bug and what did we do wrong?

Thank you!

Source: Windows Questions C++