QOpenGLWidget drawing a line. Matrix problem?

[jacubus]

Hello i have a some code which is supposed to draw a white line in QOpenGlWidget which is part of my app. I just want to create 3D space inside the app where you'll be able make some changes.
When i added matrixes and camera position the line is not visible (Previously has been displaying incorrectly but at least something has been visible, so i found out that i need to set up camera view properly and draw line basing on camera and projection)..
Camera is displaying a scene from +z and looking at 0z when the line is in -z so it should be clearly visible. Here is code

In class variables:

private:
    QOpenGLShaderProgram program;
    QOpenGLBuffer vbo;
    QOpenGLVertexArrayObject vao;
    int am = 0;

void CubeMainWidget::initializeGL()
{
    // Create a Vertex Array Object
           initializeOpenGLFunctions();

           vao.create();
           vao.bind();

           // Create a Vertex Buffer Object and copy data to it
           vbo.create();
           vbo.bind();
           am = 2;
           float vertices[] = {
               -1.0f, 0.0f, -3.0f,
               1.0f, 0.0f, -3.0f

           };
           vbo.allocate(vertices, sizeof(vertices));

           // Create a Shader Program
           program.addShaderFromSourceCode(QOpenGLShader::Vertex,
               "#version 330\n"
               "in vec3 position;\n"
               // |2|
               "uniform mat4 projection;\n"
               "uniform mat4 view;\n"
               // -|2|
               "void main()\n"
               "{\n"
               "    gl_Position = projection * view * vec4(position, 1.0);\n"
               "}\n");
           program.addShaderFromSourceCode(QOpenGLShader::Fragment,
               "#version 330\n"
               "out vec4 color;\n"
               "void main()\n"
               "{\n"
               "    color = vec4(1.0, 1.0, 1.0, 1.0);\n"
               "}\n");
           program.link();

           // Set the Vertex Array Object as the current one
           vao.bind();
           
           //! [2]
           // Enable depth buffer
           glEnable(GL_DEPTH_TEST);

           // Enable back face culling
           glEnable(GL_CULL_FACE);
           //! [2]

           // Enable attribute arrays
           program.enableAttributeArray("position");

           // Set the attribute arrays
           program.setAttributeArray("position", GL_FLOAT, 0, 3);
           
           // Release all
           vao.release();
           vbo.release();
           program.release();
}
void CubeMainWidget::resizeGL(int w, int h)
{
    // |2|
    qreal aspect = qreal(w) / qreal(h ? h : 1);
    qDebug() << qreal(w) << qreal(h) << aspect;
    QMatrix4x4 projection;
    projection.perspective(45.f, aspect, 0.01f, 100.f);
    program.setUniformValue("projection", projection);
    QMatrix4x4 view;
    view.lookAt(QVector3D(0.0f, 0.0f, 5.0f),
                QVector3D(0.0f, 0.0f, 0.0f),
                QVector3D(0.0f, 1.0f, 0.0f));
    program.setUniformValue("view", view);
}
void CubeMainWidget::paintGL()
{
    // Clear the screen
          glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

          // Use the Shader Program
          program.bind();


          // Use the Vertex Array Object
          vao.bind();

          // Draw the line
          glDrawArrays(GL_LINES, 0, am);

          // Release all
          vao.release();
          program.release();
}