Cannot instantiate Plugin with UI

I've done a QT program that loads plugins in real time and it works wonderfully.
Now I've just created a new plugin that differs from all the others because it has a .ui file as it should show a gui when executed. Well, it cannot be instantiated by the plugin loader.

I've already tried to remove only the part with the ui stuff and in that case it's instantiated (but does, of course, nothing).

Is there something I'm missing ? is it possible that the ui code makes it incompatible ?

Thanks in advance for the help.

Ok, my fault.

I forgot to include the .cpp file of the GUI in the CMakeList.txt :o
Strange I didn't get an error but now it works.