OpenGL - Defining Model Matrix via instanced attribute - c++

Question

Im fairly new to OpenGL and I'm trying to use instancing to draw many 3D rectangles. I have currently positioned each 3d rectangle in a different position and they show properly.
Problem: I now want each 3d rectangle to have a different rotation, defined by me and pass it to the vertex shader. However when I do that, The rectangles do not appear on the screen anymore.
I'm not providing the complete code because it is fairly long. I'm only providing the important part and hoping that i'm making a silly mistake somewhere and you can point it out.
Here is the vertex shader:
#version 410 core
layout (location = 0) in vec3 position;
layout (location = 1) in vec3 offset;
layout (location = 2) in vec2 texCoord;
layout (location = 3) in mat4 instanceMatrix;
uniform mat4 view;
uniform mat4 projection;
out vec2 TexCoord;
void main()
{
TexCoord = texCoord;
gl_Position = projection * view * instanceMatrix * vec4(position + offset, 1.0f) ;
}
Here is the fragment shader:
#version 410 core
out vec4 color;
void main()
{
color = vec4(1.0f,1.0f,1.0f, 1.0f);
}
Here is the C++ code from where im sending the data:
// definition of models variable : std::vector<glm::mat4> models(0);
// Sending the Model matrix for each Rectangle
GLuint buffer;
glGenBuffers(1, &buffer);
glBindBuffer(GL_ARRAY_BUFFER, buffer);
glBufferData(GL_ARRAY_BUFFER, models.size() * sizeof(glm::mat4), &models[0], GL_STATIC_DRAW);
GLsizei vec4Size = sizeof(glm::vec4);
glEnableVertexAttribArray(3);
glVertexAttribPointer(3, 4, GL_FLOAT, GL_FALSE, 4 * vec4Size, (GLvoid*)0);
glEnableVertexAttribArray(4);
glVertexAttribPointer(4, 4, GL_FLOAT, GL_FALSE, 4 * vec4Size, (GLvoid*)(vec4Size));
glEnableVertexAttribArray(5);
glVertexAttribPointer(5, 4, GL_FLOAT, GL_FALSE, 4 * vec4Size, (GLvoid*)(2 * vec4Size));
glEnableVertexAttribArray(6);
glVertexAttribPointer(6, 4, GL_FLOAT, GL_FALSE, 4 * vec4Size, (GLvoid*)(3 * vec4Size));
glVertexAttribDivisor(3, 1);
glVertexAttribDivisor(4, 1);
glVertexAttribDivisor(5, 1);
glVertexAttribDivisor(6, 1);
// unfocus
glBindBuffer(GL_ARRAY_BUFFER, 0);
glBindVertexArray(0);