I'm pretty new to C++, OpenGL and mostly CEGUI, but I am working on a school project. The main application runs fine, now I only want to add some GUI elements with CEGUI. My problem is, after calling CEGUI::OpenGLRenderer::bootstrapSystem(); I simply want to render the GUI (or do ANYTHING with CEGUI::System). But no matter what I try, my application always crashes. gDEBugger showed me it is a Second chance exception, "the thread tried to read from or write to a virtual address for which it does not have access".
Now I understand, what the exception mean and I tried to find some solution using Google of course, but right now I am simply stuck.
I am using CEGUI 0.7.5 (I know... please focus on the problem) and SDL2. I've set all search directories in code::blocks, the linker options as well and copied the required .dlls to the right folder. (Yeah, I've included the headers

If you need some code snippets, let me know, but right know I have no idea what can be wrong and I don't want to spam the forum with all my codes.

Thanks for any help in advance!