I used a PHP library, which in turn is elementary based on libraries published with an Apache 2.0 license and a LGPL license. The author himself has published his library under a GPLv2 license. Because the GPLv2 license is not compatible with Apache 2.0 license, it would have to be invalid, right? If it is invalid, then my work that only includes this library to use the API can not be a GPLv2 license either.
So is the entire construct completely unlicensed, or his derivate-library only, because he has chosen the incompatible license (GPLv2)?