AQTime displays this message when you are trying to add a 32-bit (x86) or 64-bit (x64) module to the AQTime project that already contains modules with other “bitness” (64-bit or 32-bit).
In Windows, 32-bit modules can be loaded only into 32-bit processes and 64-bit modules can be loaded only into 64-bit processes. So, having modules of both types in the same project is useless, because you cannot profile them simultaneously. If the first added module is a 32-bit module, you can then only add 32-bit modules. If the first added module is a 64-bit module, you can then only add 64-bit modules.
To change the “bitness” of the project, clear the module list and then add a module of the desired type.