I'm really desperate. I used OpenGL with C++ for months. Then I formatted my computer and, for some reason, I couldn't load textures anymore. I spread glGetError's all over my code and I saw that some part of the code was getting an error 1282, which is GL_INVALID_OPERATION. In the end, I got to the smaller code possible:
We have no idea about how the underlying implementation of the OpenGL drivers. The best you can do is read the documentation and go troubleshooting yourself. It's better to get a correct answer through documentation than getting a third-party answer through a forum post...