LibOVR + OpenGL strange behaviour

// ...
BYTE *pixels;
void initGL(void) {
    /* init GLFW, GLEW...*/
    glEnable(GL_TEXTURE_2D);
    glGenTextures(1, &gltexture);
    glBindTexture(GL_TEXTURE_2D, gltexture);
    pixels = new BYTE[texW * texH * 3];
    memset(pixels, 0x90, texW * texH * 3);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, texW, texH, 0, GL_RGB, GL_UNSIGNED_BYTE, pixels);
    glBindTexture(GL_TEXTURE_2D, 0);

    /* generate framebuffer */

    /* THIS piece of code */
    /* vvvvvvvvvvvvvvvvvv */
    glGenFramebuffers(1, &fbo);
    glBindFramebuffer(GL_FRAMEBUFFER, fbo);
    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, gltexture, 0);
    glBindFramebuffer(GL_FRAMEBUFFER, 0);
    /* ^^^^^^^^^^^^^^^^^^ */
}

/* It's standard usage */
void draw(void) {
    ovrFrameTiming hmdFrameTiming = ovrHmd_BeginFrame(hmd, 0);
    for (int i = 0; i < 2; ++i) {
        ovrEyeType eye = hmdDesc.EyeRenderOrder[i];
        ovrPosef eyePose = ovrHmd_BeginEyeRender(hmd, eye);
        ovrHmd_EndEyeRender(hmd, eye, eyePose, &eyeTexture[i].Texture);
    }

    ovrHmd_EndFrame(hmd);
}

void initOR(void) {
    // creating ovrHmd, ... ovrHmdDesc
    ovrGLConfig cfg;
    memset(&cfg, 0, sizeof(cfg));
    memset(eyes, 0, sizeof(eyes));

    cfg.OGL.Header.API = ovrRenderAPI_OpenGL;
    cfg.OGL.Header.RTSize = { screenW, screenH };
    cfg.OGL.Header.Multisample = 1;
    cfg.OGL.Window = 0;

    ovrFovPort fov[2];
    // setting fov...

    if (!ovrHmd_ConfigureRendering(hmd, &cfg.Config, ovrDistortionCap_TimeWarp | ovrDistortionCap_Chromatic | ovrDistortionCap_Vignette, fov,   eyes)) {
        MSG("Can't configure OculusRift rendering!");
        exit(EXIT_FAILURE);
    }

    for (int i = 0; i < 2; ++i) {
        eyeTexture[i].OGL.Header.API = ovrRenderAPI_OpenGL;
        eyeTexture[i].OGL.Header.TextureSize = { texW, texH };
        eyeTexture[i].OGL.Header.RenderViewport.Pos = { i*(screenW >> 1), 0 };
        eyeTexture[i].OGL.Header.RenderViewport.Size = { screenW >> 1, screenH };
        eyeTexture[i].OGL.TexId = gltexture;
    }
}

// ....