Creator can't find one specific #include file

I have a “public header” path, which I add to my project file using INCLUDEPATH += $$MY_INCLUDE_PATH I have verified using message() that the resulting INCLUDE path is correct, containing an absolute path that I can copy from the message output and paste into Explorer (Windows 7). Nevertheless, Qt Creator (2.5.2) cannot seem to locate that folder. How can I find the cause of this? Anything I can try to fix it? Edit: The compiler can find the path. So the path must be correct.